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PubMed2006

Spatial clustering of mental disorders and associated characteristics of the neighbourhood context in Malmö, Sweden, in 2001.

STUDY OBJECTIVE: Previous research provides preliminary evidence of spatial variations of mental disorders and associations between neighbourhood social context and mental health. This study expands past literature by (1) using spatial techniques, rather than multilevel models, to compare the spatial distributions of two groups of mental disorders (that is, disorders due to psychoactive substance use, and neurotic, stress related, and somatoform disorders); and (2) investigating the independent impact of contextual deprivation and neighbourhood social disorganisation on mental health, while assessing both the magnitude and the spatial scale of these effects. DESIGN: Using different spatial techniques, the study investigated mental disorders due to psychoactive substance use, and neurotic disorders. PARTICIPANTS: All 89,285 persons aged 40-69 years residing in Malmö, Sweden, in 2001, geolocated to their place of residence. MAIN RESULTS: The spatial scan statistic identified a large cluster of increased prevalence in a similar location for the two mental disorders in the northern part of Malmö. However, hierarchical geostatistical models showed that the two groups of disorders exhibited a different spatial distribution, in terms of both magnitude and spatial scale. Mental disorders due to substance consumption showed larger neighbourhood variations, and varied in space on a larger scale, than neurotic disorders. After adjustment for individual factors, the risk of substance related disorders increased with neighbourhood deprivation and neighbourhood social disorganisation. The risk of neurotic disorders only increased with contextual deprivation. Measuring contextual factors across continuous space, it was found that these associations operated on a local scale. CONCLUSIONS: Taking space into account in the analyses permitted deeper insight into the contextual determinants of mental disorders.

Adult↗
PubMed2006

Raman spectroscopy as a process analytical technology tool for the understanding and the quantitative in-line monitoring of the homogenization process of a pharmaceutical suspension.

The aim of this study was to propose a Process Analytical Technology (PAT) strategy for the quantitative in-line monitoring of an aqueous pharmaceutical suspension using Raman spectroscopy. A screening design was used to study the significance of process variables (mixing speed and height of the stirrer in the reactor) and of formulation variables (concentration of the active pharmaceutical ingredient (API) ibuprofen and the viscosity enhancer (xanthan gum)) on the time required to homogenize an aqueous pharmaceutical model suspension as response variable. Ibuprofen concentration (10% and 15% (w/v)) and the height of stirrer (position 1 and 2) were discrete variables, whereas the viscosity enhancer (concentration range: 1-2 g L-1) and the mixing speed (700-1000 rpm) were continuous variables. Next, a multilevel full factorial design was applied to study the effect of the remaining significant variables upon the homogenization process and to establish the optimum conditions for the process. Interactions between these variables were investigated as well. During each design experiment, the conformity index (CI) method was used to monitor homogeneity of the suspension mixing system in real-time using Raman spectroscopy in combination with a fibre optical immersion probe. Finally, a principal component regression (PCR) model was developed and evaluated to perform quantitative real-time and in-line measurements of the API during the mixing process. The experimental design results showed that the suspension homogenization process is an irregular process, for which it is impossible to model the studied variables upon the measured response variable. However, applying the PCR model it is possible to predict in-line and real-time the concentration of the API in a suspension during a mixing process. In this study, it is shown that Raman spectroscopy is a suitable PAT tool for the control of the homogenization process of an aqueous suspension. Raman spectroscopy not only allowed real-time monitoring of the homogeneity of the suspension, but also helped (in combination with experimental design) to understand the process. Further, the technique allowed real-time and in-line quantification of the API during the mixing process.

Chemistry, Pharmaceutical↗
PubMed1996

Disability in geriatric depression.

OBJECTIVE: The authors' purpose was to identify the relationship of disability to clinical measures that are part of a comprehensive psychiatric examination of depressed elderly patients. METHOD: The disability of 75 elderly inpatients and outpatients with major depression whose cognitive function ranged from normality to mild dementia was assessed with the Philadelphia Multilevel Assessment Instrument. Age at onset of depression, chronicity of depression, severity of depression, cognitive impairment, medical burden, social support and living environment were assessed with standardized instruments. RESULTS: Impairment in instrumental activities of daily living was significantly associated with advanced age, severity of depression, and medical burden. The relationship of depressive symptoms to impairment in instrumental activities of daily living was not influenced by age or medical burden. Anxiety and depressive ideation as well as retardation and weight loss were significantly associated with impairment in instrumental activities of daily living. Interviewer-rated global disability was associated with advanced age at onset of depression, medical burden, and overall cognitive impairment. Specifically, a disturbance in initiation and perseveration was significantly related to global disability. CONCLUSIONS: Impairment in instrumental activities of daily living appears to be a relatively independent dimension of health status that is related to depressive symptoms, particularly anxiety and depressive ideation as well as retardation and weight loss. Global disability may be associated with impairment in initiation and perseveration and with late onset of depression. These findings provide a basis for studies investigating whether psychotherapy aimed at depressive ideation and rehabilitation efforts focused on instrumental activities of daily living can improve the outcome of geriatric depression.

Activities of Daily Living↗
PubMed2000

Recovery of mandibular motion after closed and open treatment of unilateral mandibular condylar process fractures.

The purpose of this study was to determine the rate of recovery of mandibular motion in patients treated for fractures of the mandibular condylar process. One hundred and thirty-six patients (111 men, 25 women), 74 treated by closed and 62 by open methods, were included. They underwent testing of mandibular and condyle mobility at 6 weeks, 6 months, and 1, 2, and 3 years post surgery. Their ranges of motion were compared to those of 52 controls (26 men and 26 women). A jaw-tracking device was used to assess mandibular motion. Multilevel statistical models were used to assess differences between groups, and to estimate rate of recovery in the fracture patients. In general, patients with unilateral fractures of the condylar process had maximum excursions that returned to normal values within 3 years after fracture, regardless of treatment. Patients treated open exhibited a faster rate of improvement in maximum interincisal opening than patients treated closed (0.43 mm/month vs 0.15 mm/month, respectively), but part of the difference was due to a significantly smaller opening after 6 weeks for the patients treated open (38 mm vs 42 mm, respectively). Patients treated open also exhibited a faster rate of improvement in maximum excursion toward the fracture side than patients treated closed (0.10 mm/month vs 0.04 mm/month, respectively). Based upon this study, patients with unilateral fractures of the condylar process, who are treated closed and not put into maxillomandibular fixation but are instructed in physical therapy, can be expected to achieve normal maximum excursions within 3 years after treatment. Patients treated open will have reduced maximum opening initially, but may reach normal levels of opening sooner than patients treated without surgery. Patients treated without surgery may have smaller than normal excursion toward the non-fracture side for at least 3 years after fracture, especially if their fracture was at or above the condylar neck. Improvement rates for other maximum excursions are similar for patients treated with or without surgery.

Adolescent↗
PubMed2005

Neighborhood context and sexual behaviors among adolescents: findings from the national longitudinal study of adolescent health.

CONTEXT: Adolescent sexual behaviors are a significant public health concern because of the risks of STDs and the negative social consequences of teenage pregnancies. Associations between neighborhood characteristics and adolescents' initiation of sex and contraceptive use are poorly understood. METHODS: Multilevel logistic regression analyses of data from 14,151 adolescents in grades 7-12 in Wave 1 of the National Longitudinal Study of Adolescent Health examined the relationships between four neighborhood dimensions (socioeconomic characteristics, norms and opportunity structure, social disorganization, and racial and ethnic composition) and the initiation of sex and contraceptive use at first and most recent sex. Individual- and household-level covariates were family income, parental education, race and ethnicity, age and family structure. Multivariate analyses were stratified by gender. RESULTS: All four dimensions of neighborhood context were independently associated with sexual initiation. For females, living in a neighborhood with a greater concentration of youth who were idle or black residents was associated with increased odds of sexual initiation, whereas a greater concentration of married households or Hispanic residents was associated with decreased odds of initiation. Higher initiation among males was associated with a higher concentration of poverty or idle youth, while lower initiation was found with a higher concentration of affluent households or working women. The sole association with contraceptive use was that females in neighborhoods with more idle youth had a reduced likelihood of having used contraceptives at first sex. CONCLUSIONS: Neighborhood context appears to be modestly associated with the sexual initiation of adolescents. However, little support was found for neighborhood influence on contraceptive use, suggesting that other factors may play a more important role in shaping adolescents' contraceptive behaviors.

Adolescent↗
PubMed2006

Microarray tools for deciphering complex diseases.

Individual genetic findings associated with complex diseases are unlikely to fully explain their substantial impact or provide new comprehensive insights into disease pathogenesis. These also lack the comprehensive data much needed for development of new effective drugs in majority of the disease cases in a population. In fact multilevel etiologic factors underlie almost all human diseases, including: environmental causes, epigenetic factors, DNA mutations, amplifications, and deletions, RNA expression levels, protein (translation, post translation modification, localization) and combinations thereof. Each individual might consist of different combinations of these multiple etiologic factors. Integrative evaluation of all these modifications will shed light on the whole identity of the disease and the underlying molecular mechanisms. Until now it was inconceivable to have a full grasp of such a complex etiology. Microarrays enable us to interrogate the individualized various factors (DNA, RNA and protein content) involved in disease state on genome-wide scale simultaneously and expeditiously in single cell or the tissue of interest (Figure 1). The new disciplines of microarray studies in combination hold the promise of effective, current, and comprehensive understanding of complex diseases and may be a good approach for reducing the costs and time lines associated with discovery and efficacy improvement of therapeutic drugs. In the future, through utilizing the colossal amount of microarray data findings, defining the structure, function, and dynamics of entire biological pathways and cellular networks under various physiological states, and the development of robust and efficient methods for analyzing and interpreting high dimensional data, it will be possible to connect combination of experimental results with individualized disease state. This will facilitate precise diagnosis prognosis and therapy.

Alternative Splicing↗
PubMed2001

Mechanical properties of the human cervical spine as shown by three-dimensional load-displacement curves.

STUDY DESIGN: The mechanical properties of multilevel human cervical spines were investigated by applying pure rotational moments to each specimen and measuring multidirectional intervertebral motions. OBJECTIVES: To document intervertebral main and coupled motions of the cervical spine in the form of load-displacement curves. SUMMARY OF BACKGROUND DATA: Although a number of in vivo and in vitro studies have attempted to delineate normal movement patterns of the cervical spine, none has explored the complexity of the whole cervical spine as a three-dimensional structure. METHODS: Sixteen human cadaveric specimens (C0-C7) were used for this study. Pure rotational moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied using a specially designed loading fixture. The resulting intervertebral motions were recorded using stereophotogrammetry and depicted as a series of load-displacement curves. RESULTS: The resulting load-displacement curves were found to be nonlinear, and both rotation and translation motions were coupled with main motions. With flexion-extension moment loading, the greatest degree of flexion occurred at C1-C2 (12.3 degrees), whereas the greatest degree of extension was observed at C0-C1 (20.2 degrees). With axial moment loading, rotation at C1-C2 was the largest recorded (56.7 degrees). With lateral bending moments, the average range of motion for all vertebral levels was 7.9 degrees. CONCLUSIONS: The findings of the present study are relevant to the clinical practice of examining motions of the cervical spine in three dimensions and to the understanding of spinal trauma and degenerative diseases.

Analysis of Variance↗
PubMed2003

Patient, physician, and community factors affecting referrals to specialists in Ontario, Canada: a population-based, multi-level modelling approach.

QUESTION ADDRESSED: This population-based study examines the factors affecting referrals by primary care physicians (PCPs) to specialists. MATERIALS AND METHODS: Multilevel Poisson models were used to test the impact of patient, physician and community-level variables on the referral rate (the number of office-based specialist referrals per patient by the patient's customary PCP in fiscal year 1997/98). Patients from each of 6972 PCPs with sufficient data in Ontario were examined. RESULTS: The average patient had 0.56 referrals per year (range 0-61). Referrals were higher at ages 1 and 77 to 78, and among women of childbearing age. Chronic disease variables were strongly correlated with referral rates. Patients in poor neighborhoods had more referrals, because they had more chronic diseases. After controlling for disease, individuals in the top 9% wealthiest neighborhoods had 4% more referrals. Female physicians made 8% more referrals than men. Older physicians referred more because they saw older patients; after controlling for patient age, physician age had no effect. Referrals were 14% higher in cities with medical schools compared with other cities and 12% lower in small towns. However, local specialist supply was unrelated to referral rates. CONCLUSION: This study improves our understanding of the impact of physician gender and age on referrals. It suggests that community type, not specialist supply, predicts variations in referrals. Lastly, it identifies preferential access to specialists among high-income earners, even within Canada's universal health insurance system. However, this effect is modest, suggesting that the system does provide reasonably equitable access to referrals.

Adolescent↗
PubMed2005

Preoperative "fentanyl challenge" as a tool to estimate postoperative opioid dosing in chronic opioid-consuming patients.

UNLABELLED: When opioids are used for postoperative pain control, it is useful to define the dose-response relationship for analgesia and respiratory depression. We studied 20 chronically opioid-consuming patients having elective multilevel spine fusion. Preoperatively, each patient received a fentanyl infusion of 2 microg x kg(-1) x min(-1) until the respiratory rate was <5 breaths/min. Pharmacokinetic simulations were used to estimate the effect site concentration at the time of respiratory depression and to predict the patient-controlled analgesia settings that would provide an effect-site fentanyl concentration that was 30% of the concentration associated with respiratory depression. Postoperatively, patient-controlled analgesia settings were adjusted to achieve 2-3 demand doses per hour. At steady-state patient-controlled analgesia settings, arterial blood gases and plasma fentanyl levels were measured. Sixteen patients required no adjustment or one patient-controlled analgesia adjustment. The median arterial Pco(2) level was 41 mm Hg and the interquartile range was 39-46 mm Hg. Plasma fentanyl levels demonstrated a significant correlation to the estimated effect-site concentration associated with respiratory depression determined during the preoperative fentanyl challenge. A preoperative fentanyl challenge used with pharmacokinetic simulations may be a useful tool to individualize the administration of analgesics to chronically opioid-consuming patients. IMPLICATIONS: In chronically opioid-consuming patients, doses causing respiratory depression and analgesia may differ from those in opioid-naive individuals. A preoperative infusion of fentanyl, used in conjunction with pharmacokinetic simulation, may be a valuable tool for identifying clinical end-points, such as respiratory depression and analgesia, and individualizing postoperative treatment of pain in patients who chronically consume opioids.

Analgesics, Opioid↗
PubMed2006

The impact of the Calman-Hine report on the processes and outcomes of care for Yorkshire's colorectal cancer patients.

The 1995 Calman-Hine plan outlined radical reform of the UK's cancer services with the aim of improving outcomes and reducing inequalities in NHS cancer care. Its main recommendation was to concentrate care into the hands of site-specialist, multi-disciplinary teams. This study aimed to determine if the implementation of Calman-Hine cancer teams was associated with improved processes and outcomes of care for colorectal cancer patients. The design included longitudinal survey of 13 colorectal cancer teams in Yorkshire and retrospective study of population-based data collected by the Northern and Yorkshire Cancer Registry and Information Service. The population was all colorectal cancer patients diagnosed and treated in Yorkshire between 1995 and 2000. The main outcome measures were: variations in the use of anterior resection and preoperative radiotherapy in rectal cancer, chemotherapy in Dukes stage C and D patients, and five-year survival. Using multilevel models, these outcomes were assessed in relation to measures of the extent of Calman-Hine implementation throughout the study period, namely: (i) each team's degree of adherence to the Manual of Cancer Service Standards (which outlines the specification of the 'ideal' colorectal cancer team) and (ii) the extent of site specialisation of each team's surgeons. Variation was observed in the extent to which the colorectal cancer teams in Yorkshire had conformed to the Calman-Hine recommendations. An increase in surgical site specialisation was associated with increased use of preoperative radiotherapy (OR=1.43, 95% CI=1.04-1.98, P<0.04) and anterior resection (OR=1.43, 95% CI=1.16-1.76, P<0.01) in rectal cancer patients. Increases in adherence to the Manual of Cancer Service Standards was associated with improved five-year survival after adjustment for the casemix factors of age, stage of disease, socioeconomic status and year of diagnosis, especially for colon cancer (HR=0.97, 95% CI=0.94-0.99 P<0.01). There was a similar trend of improved survival in relation to increased surgical site specialisation for rectal cancer, although the effect was not statistically significant (HR=0.93, 95% CI=0.84-1.03, P=0.15). In conclusion, the extent of implementation of the Calman-Hine report has been variable and its recommendations are associated with improvements in processes and outcomes of care for colorectal cancer patients.

Aged↗
PubMed2006

Relationship between quality of care and racial disparities in Medicare health plans.

CONTEXT: Overall quality of care and racial disparities in quality are important and related problems in health care, but their relationship has not been well studied. In the Medicare managed care program, broad improvements in quality have been accompanied by reduced racial gaps in processes of care, but substantial disparities in outcomes have persisted. OBJECTIVES: To assess variations among Medicare health plans in overall quality and racial disparity in 4 Health Plan Employer and Data Information Set (HEDIS) outcome measures, to determine whether high-performing plans exhibit smaller racial disparities, and to identify plans with high quality and low disparity. DESIGN, SETTING, AND PATIENTS: We assessed the relationship between quality and racial disparity using multilevel multivariable regression models. The study sample included 431,573 individual-level observations in 151 Medicare health plans from 2002 to 2004. MAIN OUTCOME MEASURES: Hemoglobin A(1c) of less than 9.5% or less than 9.0% for enrollees with diabetes; low-density lipoprotein cholesterol level of less than 130 mg/dL for enrollees with diabetes or after a coronary event; and blood pressure of less than 140/90 mm Hg for enrollees with hypertension. RESULTS: Clinical performance on HEDIS outcome measures was 6.8% to 14.4% lower for black enrollees than for white enrollees (P<.001 for all). For each measure, more than 70% of this disparity was due to different outcomes for black and white individuals enrolled in the same health plan rather than selection of black enrollees into lower-performing plans. Health plans varied substantially in both overall quality and racial disparity on each of the 4 outcome measures. Adjusted correlations between overall quality and racial disparity were small and not statistically significant, ranging from 0.01 (blood pressure control) to -0.21 (cholesterol control in diabetes). Only 1 health plan achieved both high quality and low disparity on more than 1 measure. CONCLUSIONS: In Medicare health plans, disparities vary widely and are only weakly correlated with the overall quality of care. Therefore, plan-specific performance reports of racial disparities on outcome measures would provide useful information not currently conveyed by standard HEDIS reports.

Black or African American↗
PubMed2006

Long-term results of the Konno procedure for complex left ventricular outflow tract obstruction.

OBJECTIVE: This study was undertaken to determine long-term clinical and echocardiographic outcomes after the Konno procedure. METHODS: Fifty-three patients who underwent the Konno procedure between January 1, 1980, and January 1, 2004, were reviewed. RESULTS: Mean age at operation was 19 years (range, 1-65 years). Indications were as follows: complex subaortic or tunnel stenosis in 22 (41%), multilevel left ventricular outflow tract obstruction in 20 (38%), and aortic valve stenosis or hypoplasia in 11 (21%). Before the Konno procedure, 66 operations were performed in 41 (77%) patients. Thirty-three (62%) patients had greater than New York Heart Association class I symptoms preoperatively. A mechanical aortic valve was implanted in 40 (75%), a homograft in 10 (19%), and a xenograft prosthesis in 3 (6%). Mortality at 30 days was 8% (n = 4). Survival at 10 years was 86%. Risk factors for overall mortality were New York Heart Association class (hazard ratio 2.22, P = .04) and longer bypass time (hazard ratio 1.93/hour, P = .04). The cumulative probability of aortic valve reoperation was 19% at 5 years and 39% at 10 years, occurring in 15 patients at a median of 3.8 years. The average left ventricular outflow tract mean gradients were 19 mm Hg at 1 year (n = 9), 13 mm Hg at 1 to 3 years (n = 9), and 13 mm Hg at 3 to 5 years (n = 5). Pulmonary regurgitation was detected in 6 patients. Pulmonary valve replacement was performed in 3 (6%). At the date of last contact, all patients for whom data was available were in New York Heart Association functional class I or II. CONCLUSION: The Konno procedure is effective, allowing both long-term reduction of left ventricular outflow tract obstruction and improvement in functional class. Prosthetic aortic valve and native pulmonary valve complications may necessitate reoperation.

Adolescent↗
PubMed1999

Intestinal parasites in swine in the Nordic countries: multilevel modelling of Ascaris suum infections in relation to production factors.

In Denmark, Finland, Iceland, Norway and Sweden, 413 sow herds were randomly selected for sampling. Faeces from pigs of 7 age groups/categories were examined for helminth eggs (11,233 individual samples), and an accompanying questionnaire was completed at each visit. In total, 1138 pigs on 230 farms were found to be positive for Ascaris suum. Considerable differences in the occurrence of A. suum could be observed directly for several of 20 independent variables at the herd or category level. However, given that univariate analyses may be severely affected by confounding of covariates resulting in spurious inference, additional multivariate analyses were undertaken. An ordinary logistic regression on Ascaris positive/negative farms showed that Denmark had the highest frequency of infected herds, while Iceland and Finland had the lowest frequencies and that herds using 'late weaning' and 'Class 2' drugs (pyrantel, levamisole) were most often infected. Because many herds were found to be totally negative for A. suum, mixed hierarchical logistic-normal regression models (both the penalized quasi-likelihood and the Markov Chain Monte Carlo methods) were developed for both a full (all herds) and a reduced (the 230 infected herds) data set using either a cut-off of > 0 eggs per gram (epg) or > 200 epg to counter for false-positive egg counts. Estimates for identical models, but where the animal level variance was constrained to the binomial assumption, were also calculated. Significant covariates were robust to model development with 'Age group', 'Country', 'Weaning age', 'Water system' and simple interactions between the latter two and 'Age group' being significantly associated with the occurrence of A. suum, while all variables concerning anthelmintic drug, anthelmintic strategy, floor type, bedding, dung removal, washing and disinfection were not. These findings are discussed in the light of the complex relationship between A. suum and its pig host.

Age Factors↗
PubMed2006

Electronic momentary assessment in chronic pain II: pain and psychological pain responses as predictors of pain disability.

OBJECTIVES AND METHODS: More than 7,100 electronic diaries from 80 patients with chronic pain (mean: 89.3, range 30-115) entered multilevel analyses to establish the statistical prediction of disability by pain intensity and by psychological functioning (fear avoidance, cognitive, and spousal pain responses). We also tested the differences between pre-chronic, recently chronic, and persistently chronic pain in the prediction of disability (impaired physical and mental capacity, pain interference with activities, immobility due to pain). RESULTS: Pain intensity explained 8% to 19% of the disability variance. Beyond this psychological functioning explained 7% to 16%: particularly fear-avoidance and cognitive pain responses predicted chronic pain disorder disability; spousal responses predicted immobility better than other aspects of disability. Immobility due to actual pain occurred infrequently. When it did, however, it was better predicted by avoidance behavior in the patient and by spousal discouragement of movement than by actual pain intensity. The prediction of immobility due to pain by, respectively, avoidance behavior and catastrophizing was better in chronic pain (>6 months) and that of physical impairment by catastrophizing better in persistently chronic pain (>12 months) than in pain of shorter duration. DISCUSSION: The psychological prediction of chronic pain disorder disability was determined beyond that accounted for by pain intensity. Nonetheless, psychological functioning explained substantial variance in chronic pain disorder disability. The psychological prediction of immobility and physical impairment was stronger with longer pain duration. Patient characteristics and momentary states of disability-and in particular of immobility-should be carefully distinguished and accounted for in chronic pain disorder.

Adult↗
PubMed1996

Getting started--a review of physical activity adoption studies.

The aim of this paper has been to review methods that have been found to be effective in getting sedentary adults to adopt physical activity, to examine these methods within the multilevel framework conceptualised by Winett et al, and to provide recommendations for future research to test new methods and their effectiveness in leading to the adoption of physical activity in sedentary populations. Searches for relevant studies were conducted on the Medline computerised database. Additional studies were located in reference sections of these studies and other review papers. Surveys that specifically identified determinants of adoption of physical activity in adults were included. Reviewed articles were selected on the basis of quasi-experimental and experimental designs that specifically examined the question of how to get sedentary adults to adopt a programme of physical activity or exercise, had completely described methods, and evaluated the effectiveness of methods of increasing physical activity and/or exercise. While numerous reviews have been written on determinants on physical activity adoption and maintenance, only two prospective surveys have identified specifics of adoption of physical activity. Most of the evidence for techniques that help inactive people to adopt physical activity comes from quasi-experimental and experimental intervention studies examining various cognitive and behavioural strategies at the individual level. Fewer studies have examined techniques at the interpersonal, organisational, community, environmental, and policy level. More prospective observational studies aimed at homogeneous subgroups are needed to identify correlates of physical activity adoption to help tailor interventions. Continued clinical studies are needed to differentiate the necessary and sufficient strategies at the personal and interpersonal levels. Interventions aimed at environmental, institutional, and social levels remain largely unexplored and there is a need for more research that specifically targets inactive subgroups at these levels.

Adult↗
PubMed1999

What determines geographical variation in rates of acceptance onto renal replacement therapy in England?

OBJECTIVE: To determine the independent effects of need and supply factors on the known geographical variation in acceptance rates onto renal replacement therapy (RRT) in England. METHODS: Data were obtained from all renal units in England on the characteristics of all cases aged 16 years and over, resident in England, who were accepted onto RRT in 1991 and 1992. Of these, 5715 (94.5%) had a valid postcode that could be matched to a census ward. Multilevel modelling using Poisson regression was used. The number of acceptances in each census ward within age bands 16-34, 35-64 and 65+ was the dependent variable. Independent effects modelled were: (1) individual factors (age, sex); (2) census ward need factors--ethnicity (expressed as the percentage of the ward population that was Asian or African-Caribbean), socio-economic deprivation--and supply factors--'access' to the nearest renal unit using crowfly and road travel time and distance, and services available to each ward expressed as number of haemodialysis stations per 100,000 catchment population of the nearest renal unit; (3) district health authority level effects. RESULTS: Age was a major determinant of acceptance, with a 7-fold higher rate in males aged over 64 years compared with younger men. Acceptance rates were lower in females, with a negative age-sex interaction in females aged over 64 years. The percentage of both Asian and African-Caribbean populations per ward was a highly significant positive determinant. Deprivation was also a significant determinant, best represented by a customised index. There was an inverse relation of acceptance with distance, especially road travel time. Other supply side variables had a significant effect though there was no independent district effect. There was some variation in the strength of these relationships by type of area (Greater London, urban and non-urban). CONCLUSIONS: Need and supply factors influence service use as expressed as acceptance onto RRT. Pressure to expand RRT services needs to be aimed at areas with large minority ethnic populations and those living far from existing units.

Adolescent↗
PubMed2006

Biomechanical analysis of rotational motions after disc arthroplasty: implications for patients with adult deformities.

STUDY DESIGN: An anatomic and biomechanical bench-top basic scientific comparative analysis to determine the appropriateness of total disc replacement (TDR) in a lumbar spine with scoliotic tendencies. OBJECTIVES: Only limited data are currently available studying the application of disc replacement adjacent to scoliosis fusions. Theoretically, motion preservation should help delay the continuum of lumbar degeneration adjacent to scoliosis fusions and rotationally unstable lumbar segments. SUMMARY OF BACKGROUND DATA: As a tertiary referral center for failed TDR, we noticed an alarming number of lumbar spinal rotational iatrogenic instability patterns but none occurring in the cervical spine. It is appropriate to analyze the bench-top rotational stability of disc replacement to predict whether this new technology is feasible for a larger prospective clinical study in the treatment of degenerative scoliosis. METHODS: Measurements were taken from 60 human specimens from the Hamann-Todd Osteological Collection: 1) to determine the rotational arc of influence (AOI) = the angle formed from the center of axial rotation to the outermost extent of the facet joints; and 2) to determine the relative anatomic size discrepancy between the left and right facets proportionately with the cross-sectional area of the intervertebral disc = facet/endplate ratio (FER). Biomechanical testing was performed using fresh frozen human cadaveric spines with the following conditions to determine the rotational stability: 1) intact; 2) resection of ALL, anulus, disc, and PLL simulating the preparation for a TDR; 3) a more radical anular resection; 4) entire 360 degrees anular resection; and 4) insertion of the respective unconstrained-type disc replacement. Using a 6 degrees of freedom spine simulator, unconstrained pure moments of +/-8.0 Nm (lumbar) and +/-3.0 Nm (cervical) were used for axial rotation with quantification of the operative level range of motion and neutral zone, with data normalized to the intact spine condition. RESULTS: There were anatomic limitations in the lumbar spine that make it less desirable to apply uncon-strained disc replacements; indeed, the spine was at risk for iatrogenic lumbar scoliosis. The anulus fibrosis, anterior longitudinal ligament, and the posterior longitudinal ligament are critical structures in preventing iatrogenic scoliosis. The lumbar facet joints are more posteriorly located and are smaller relative to the intervertebral disc, compared with this association in the cervical spine. Because the facet capsular ligaments are mechanically less effective with lower tensile strength in the lumbar spine, multiple-level arthroplasty tends to accentuate scoliotic tendencies; this is independent of prosthetic design and surgical technique. DISCUSSION: Implantation of the lumbar TDR never restored the motion segment back to the rotational stability of the intact segment achieving a range of 120% to 140% rotational range of motion compared with the intact condition. This rotational instability proved to be additive as a two-level lumbar TDR resulted in between 240% and 260% increase in rotational instability compared with the intact condition. CONCLUSION: The neutral zone of the intact cervical spine was restored even using an unconstrained cervical TDR. The greater inherent rotational constraints of the cervical spine make it more amenable to stable multilevel arthroplasty compared with the lumbar spine.

Adult↗
PubMed2001

Infrainguinal arterial reconstructions in patients with aortoiliac occlusive disease: the influence of iliac stenting.

OBJECTIVE: Iliac artery angioplasty (IAA) is an effective adjunct when combined with infrainguinal arterial reconstructions (IARs) in appropriate patients with multilevel occlusive disease. However, the effect of iliac artery stenting (IAS) on the outcome of patients undergoing distal bypass procedures is not defined. The purpose of this study was to estimate the influence of previous IAS for iliac occlusive disease on the outcome of IARs, compared with those after IAA alone or aortofemoral bypass grafting procedures (AFBs). METHODS: During a 5-year period (1995-2000), 105 patients with previous intervention for iliac occlusive disease underwent 120 IARs. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association between preoperative variables and cumulative primary patency. RESULTS: Forty-five IARs were performed in patients with an earlier IAS repair, 33 in patients with an earlier IAA repair, and 42 in patients with an earlier AFB repair. There were not significant differences between patients in the IAS and IAA groups, except for a more frequent use of polytetrafluoroethylene grafts for IARs in the IAS group (40% vs 15%; chi(2) test, P = .03). The 5-year primary patency rate for IARs was 68% in the IAS group, 46% in the IAA group, and 61% in the AFB group. Univariate analyses revealed that primary patency rates for IARs in patients with previous IAS were significantly higher than those in the IAA group (Kaplan-Meier, log-rank test, P = .02). Previous IAA repair was associated with a two-fold increased risk of IAR graft failure (relative risk, 2.2; 95% CI, 1.1-4.8; P = .04). CONCLUSIONS: IARs in patients with previous IAS have significantly improved graft patency, compared with those in patients with previous IAA alone. Such graft patency for IAR after IAS is similar to that obtained after AFB repair.

Adult↗