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Biomedical subjects

K Lawrence

Publications and source records attributed to K Lawrence.

At least 19 recordsLinked to original sources
PubMed1999

Utilization of health care resources by obese Canadians.

BACKGROUND: The prevalence of obesity in Canada has been increasing in recent years. Using data from the National Population Health Survey (NPHS), the authors determined the prevalence of obesity among Canadians, the associated comorbidities and the patterns of resource utilization by obese people. METHODS: The NPHS, a cross-sectional survey conducted in 1994, was administered to 17,626 Canadians 12 years of age or older who were not long-term residents of hospitals or long-term care facilities and were not residing on First Nations reserves or Canadian Armed Forces bases, or in the Yukon and Northwest Territories. For the authors' analysis, the study population consisted of 12,318 Canadians aged 20-64 years who were not pregnant and for whom the body mass index (BMI) had been calculated. The prevalence of comorbidities, health status index scores, self-esteem, self-rated health, restriction of activity, health care resource utilization (physician visits, disability days, admissions to hospital and medication use) were determined for obese people (BMI of 27 or greater) and nonobese people. RESULTS: The NPHS data revealed that 35.2% of men and 25.8% of women in Canada were obese in 1994. Obese respondents were more likely than nonobese respondents to suffer from stress (adjusted odds ratio [OR] 1.20, 95% confidence interval [CI] 1.11-1.31), activity restrictions (adjusted OR 1.39, 95% CI 1.26-1.54) and a number of chronic comorbidities. Obese respondents were also more likely to consult with physicians (adjusted OR 1.32, 95% CI 1.22-1.43), be prescribed a number of medications and to require excess disability days (adjusted OR 1.22, 95% CI 1.08-1.36). INTERPRETATION: Obesity represents a substantial burden on the health of Canadians and on Canada's health care resources.

Adult↗
PubMed1998

Analysis of Canadian population with potential geographic access to intravenous thrombolysis for acute ischemic stroke.

BACKGROUND AND PURPOSE: We sought to identify the Canadian population with potential access to intravenous tissue plasminogen activator within 3 hours of onset of acute ischemic stroke. METHODS: Assuming that 60 minutes is needed for stroke recognition, emergency room evaluation, and administration of tissue plasminogen activator, 120 minutes remain for transport, using a 3-hour treatment window. Ambulance databases were analyzed for transport times of 60, 90, and 120 minutes and were found to correspond to transport distances of 32, 64, and 105 kilometers (20, 40, and 65 miles), respectively. Using Geographical Information System (GIS) software, these radii were overlaid on thematic maps of Canadian hospitals identified as having a third- or fourth-generation CT and with a neurologist and an emergency physician on staff. Analysis was then performed on complete Canadian census data from 1991 and the interim 1996 census count. RESULTS: 67.3%, 78.2%, and 85.3% of the total Canadian population were within 32, 64, and 105 kilometers, respectively, of an identified hospital. For individuals >/=65 years of age, 64.4%, 77.0%, and 85.7% were within the respective radii. Complete analysis by age, ethnic origin, and gender are detailed. CONCLUSIONS: In the model described, a substantial percentage of the Canadian population has geographic access to a hospital potentially capable of delivering intravenous thrombolysis for acute ischemic stroke. GIS analysis can identify both population groups and rural areas with limited access to thrombolytic stroke treatment. A coordinated emergency medical service response for stroke is advocated to maximize coverage, as a 60-minute delay in emergency room arrival eliminated 5.1 million people from potential treatment.

Acute Disease↗
PubMed1998

Stability of diltiazem in whole blood: forensic implications.

The stability of diltiazem (DTZ) in whole blood and in postmortem samples was investigated. In the first study, an aliquot of outdated Red Cross blood with sodium fluoride added as a preservative was spiked with DTZ and stored for one year under three separate conditions: room temperature, 4 degrees C, and -20 degrees C. DTZ and one of its major metabolites, desacetyldiltiazem (DAD), were quantitated at given intervals during this period. In the second study, case postmortem blood samples (n = 36) that exhibited different degrees of putrefaction were spiked in a similar fashion and the stability of DTZ was determined after storage at 4 degrees C for 92 days. DTZ and DAD were extracted as bases, using mild pH conditions to prevent the hydrolysis of DTZ, and quantitated by an HPLC system equipped with a diode array detector and a Supelcosil LCDP column, 5 microns, 250 mm x 4.6 mm inside diameter. Approximately 50% of DTZ was lost in the Red Cross blood stored at room temperature and 4 degrees C, after 19 and 124 days, respectively. This was associated with concomitant appearance and comparable increase in DAD concentration, presumably due to the in vitro hydrolysis of DTZ to DAD. No significant loss of DTZ was observed in the -20 degrees C samples. Similar changes in DTZ and DAD concentrations were seen in postmortem blood samples stored at 4 degrees C for 92 days, though notably, the extent of loss of DTZ varied from complete to negligible. The data suggest that the potential for in vitro conversion of DTZ to DAD should be considered for proper interpretation of postmortem DTZ/DAD findings. Several cases examined in this laboratory will be used to discuss other forensic implications.

Adult↗
PubMed1997

A shorter form health survey: can the SF-12 replicate results from the SF-36 in longitudinal studies?

BACKGROUND: The SF-36 is a generic health status measure which has gained popularity as a measure of outcome in a wide variety of patient groups and social surveys. However, there is a need for even shorter measures, which reduce respondent burden. The developers of the SF-36 have consequently suggested that a 12-item sub-set of the items may accurately reproduce the two summary component scores which can be derived from the SF-36 [the Physical Component Summary Score (PCS) and Mental Health Component Summary Score (MCS)]. In this paper, we adopt scoring algorithms for the UK SF-36 and SF-12 summary scores to evaluate the picture of change gained in various treatment groups. METHODS: The SF-36 was administered in three treatment groups (ACE inhibitors for congestive heart failure, continuous positive airways therapy for sleep apnoea, and open vs laparoscopic surgery for inguinal hernia). RESULTS: PCS and MCS scores calculated from the SF-36 or a sub-set of 12 items (the 'SF-12') were virtually identical, and indicated the same magnitude of ill-health and degree of change over time. CONCLUSION: The results suggest that where two summary scores of health status are adequate than the SF-12 may be the instrument of choice.

Adult↗
PubMed1997

Evaluation of index and profile measures of health status in a randomized controlled trial. Comparison of the Medical Outcomes Study 36-Item Short Form Health Survey, EuroQol, and disease specific measures.

OBJECTIVES: The authors compare two generic measures of health status with disease-specific measures in a randomized controlled trial of transurethral resection of the prostate with laser vaporization prostatectomy for benign prostatic hypertrophy. METHODS: Patients entered into the trial completed the following questionnaires prior to treatment and at follow-up at 3 months and 1 year. The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) is a generic measure that produces an eight-dimension profile as well as two summary measures of health status (the physical component score and the mental component score). The EuroQol provides two single index measures of health status; one intended to convey the utility (or lack of) that an individual derives from his or her own health state compared with alternative states and a second simple visual analog scale "thermometer" of health status. The American Urological Association symptom score and the Bothersome index are disease-specific indices of health status for use specifically with benign prostatic hypertrophy patients. RESULTS: The EuroQol indicates no statistically significant improvements with time for either arm of the trial. The SF-36 physical and general health perceptions domains indicates statistically significant improvements for the transurethral resection of the prostate arm alone at 3 months and 1 year, as do the physical summary score at the 3-month follow-up visit. The effect sizes of these improvements, however, are small, using standard criteria. In contrast, statistically significant differences are found with time for both transurethral resection of the prostate and laser prostatectomy on both disease-specific measures, which also indicate statistically significant superior outcome for the transurethral resection of the prostate arm compared with the laser arm. CONCLUSIONS: The results indicate that the disease-specific measures are more sensitive to change than the generic measures of outcome. Possible explanations for this are discussed.

Follow-Up Studies↗
PubMed1997

Oral administration of tylosin phosphate for treatment and prevention of proliferative enteropathy in pigs.

OBJECTIVE: To evaluate the efficacy of orally administered tylosin phosphate for prevention and treatment proliferative enteropathy (PE) in pigs. ANIMALS: Crossbred pigs weaned at 24 days of age. PROCEDURE: Pigs were challenge exposed with an inoculum of Lawsonia intracellularis strain LR189/5/83. Seven control pigs received buffer solution. Of 33 challenge-exposed pigs, 8 were untreated. Two groups of challenge-exposed pigs were dosed orally with tylosin phosphate via a 2% stabilized premix, starting with 100 or 40 ppm 4 days before challenge exposure and continuing for 16 days, when the dose was reduced to 40 or 20 ppm, respectively, which was continued for 12 more days. Another group of challenge-exposed pigs was dosed orally with 100 ppm of tylosin phosphate commencing 7 days after challenge exposure and continuing for 21 days. Pigs were euthanatized and necropsied 4 weeks after challenge exposure. RESULTS: The 8 untreated pigs had reduced weight gain, 3 of them had moderate diarrhea 3 weeks after challenge exposure. Five pigs had gross lesions of PE at necropsy. Seven pigs had histologic lesions of PE with numerous L intracellularis organisms. None of the pigs in the control, nonchallenge-exposed, or the 3 groups given tylosin phosphate before or after challenge exposure had clinical signs or lesions of PE. CONCLUSION AND CLINICAL IMPLICATIONS: Tylosin phosphate can be effective for prevention and for treatment of PE, using reported dosing schedules. We can experimentally induce PE, using the pure culture challenge-exposure model, for use in testing of treatments.

Administration, Oral↗
PubMed1997

Quality of life in patients undergoing inguinal hernia repair.

Inguinal hernia repair is one of the most common surgical procedures undertaken in the NHS. Despite this, no previous work has examined quality of life in this patient group. This study examines quality of life preoperatively and at 3 and 6 months postoperatively in 140 patients undergoing inguinal hernia repair in the context of a randomised controlled trial of laparoscopic versus open hernia repair. Surgery was undertaken on a day case basis, and quality of life was assessed using the Short Form 36 (SF36). In the initial phase of the study, 57% of those screened for suitability met the study inclusion criteria and were randomised. No significant differences were found between laparoscopic and open hernia repair in terms of quality of life at 3 and 6 months postoperatively. No difference was found between 3 and 6 month scores, suggesting that patients had already made a good recovery by 3 months. A significant improvement was found between preoperative and postoperative scores, with the greatest change arising on dimensions assessing pain, physical function, and role limitation owing to physical restriction. After standardising for age, sex, and social class, a comparison of the hernia patients to population norms for the SF36 was consistent with improvement from preoperative to postoperative assessment. This study has demonstrated the improvement in quality of life in patients undergoing elective inguinal hernia repair by experienced surgeons on a day case basis. It has also demonstrated the feasibility of assessing quality of life using generic measures in this patient group. Further work in this area is required. Ultimately, the priority given to elective inguinal hernia repair will depend on how the demonstrated benefits compare with those derived from other elective surgical procedures.

Adolescent↗
PubMed1997

Pharmaceutical policies in Canadian family medicine training. Survey of residency programs.

OBJECTIVE: To determine whether family medicine residency training programs have formal policies regarding interactions between residents and the pharmaceutical industry, to identify existing practices, and to find out what issues in industry-physician interaction are addressed during the 2-year core curriculum training in Canada. DESIGN: Mailed survey using a questionnaire. SETTING: The 16 Canadian residency training programs in family medicine. PARTICIPANTS: Program directors of all 16 Canadian family medicine residency training programs replied. MAIN OUTCOME MEASURES: Number of programs with formal pharmaceutical policies; number of programs offering formal curriculum coverage of related topics in the field; program practices regarding industry sampling, detailing, sponsorship, and access. RESULTS: Only four of the 16 programs have formal policies or guidelines. Topics generally covered in core curriculum included critical appraisal (13/16) and cost trends (11/16). Few programs address determinants of prescribing (5/16), marketing techniques (4/16), provincial drug access programs (6/16), or the Canadian Medical Association guidelines on physician-industry interaction (5/16). Industry presence and sponsorship in family medicine training is notable, and screening is limited. Great variation exists, and programs are interested in future initiatives. CONCLUSIONS: Family medicine training in Canada is attempting to address pharmaceutical issues. Interest is strong, but these issues need to be given more emphasis.

Canada↗
PubMed1996

An economic evaluation of laparoscopic versus open inguinal hernia repair.

BACKGROUND: The rapid and widespread introduction of minimal access surgery has major implications for the National Health Service. It cannot be assumed that replacing an open procedure with a minimal access alternative will be cost-effective. Laparoscopic inguinal hernia repair is a procedure for which the potential economic benefits are particularly unclear. It is currently being adopted in many centres, although limited evidence on its clinical and cost-effectiveness exists. METHODS: This economic comparison of laparoscopic versus open hernia repair was undertaken on data collected on 104 patients undergoing surgery on a day case basis, in the context of a randomized controlled trial. RESULTS: The mean total health service cost of laparoscopic repair was 1074 pounds versus 489 pounds for open repair [mean difference in total health service costs 583 pounds; 95 percent confidence interval (CI) 265 pounds-904 pounds]. This difference was largely accounted for by the difference in theatre costs. Laparoscopic repair remained significantly more expensive for most but not all of the scenarios explored in the sensitivity analysis. The direction of the cost-effectiveness ratio was not sensitive to assumptions about long-term recurrence. Neither was it sensitive to halving the operating time in the laparoscopic arm of the trial. When both operating time and the costs of consumables were reduced, laparoscopic repair remained more expensive, but results for this scenario did not achieve statistical significance on this sample size. CONCLUSIONS: Laparoscopic hernia repair appears an expensive option in most plausible situations. Furthermore, many uncertainties still exist about long-term outcome after the procedure and about the conditions necessary to maximize cost-effectiveness. Large-scale randomized studies to evaluate laparoscopic hernia repair are currently under way to address these issues. We suggest that further evidence is awaited before this technology is further diffused.

Adolescent↗
PubMed1996

Relationship between health status and postoperative return to work.

BACKGROUND: Time back to work or normal activity is often regarded as an outcome measure of interest after surgery. It has recently been used as a way of quantifying the benefits of minimal access surgery. However, the extent to which variation in time back to normal reflects differences in health status is unclear. METHODS: The relationship was examined in 140 patients recovering from inguinal hernia repair. A multi-dimensional measure of health status, the Short Form 36 (SF-36), was administered preoperatively, and at ten days and six weeks postoperatively. The relationship between scores on the SF-36 dimensions and return to normal activity was examined using correlation statistics and stepwise regression. RESULTS: Health status dimensions measuring role limitation owing to physical restriction at 10 days and 6 weeks, and role limitation owing to mental problems at ten days were associated with time to return to normal on univariate analysis. Social class was also strongly associated. Using stepwise regression these two dimensions of health status together explained 33 per cent of the variance in time to normal. Other factors unrelated to health status clearly contributed to this outcome. CONCLUSION: Time back to normal activity postoperatively is influenced by a number of factors unrelated to health status and is an unreliable proxy for it. Time to normal is therefore, not a good outcome measure for quantifying the benefits of surgical interventions. Claims currently being made to justify investment in some minimal access interventions should be interpreted in the light of this.

Activities of Daily Living↗
PubMed1995

Randomised controlled trial of laparoscopic versus open repair of inguinal hernia: early results.

OBJECTIVE: To establish the safety, short term outcome, and theatre costs of transabdominal laparoscopic repair of inguinal hernia performed as day surgery. DESIGN: Randomised controlled trial. The control operation was the two layer modified Maloney darn. SETTING: Teaching hospital and district general hospital. SUBJECTS: 125 men randomised to laparoscopic or open repair of inguinal hernia. OUTCOME MEASURES: Morbidity, postoperative pain and use of analgesics, quality of life, and theatre costs. Outcome was assessed by questionnaires administered to patients daily for 10 days and at six weeks postoperatively and by outpatient review at six weeks. Return to normal activity was assessed by questionnaire at three months. RESULTS: One vascular complication (2%) occurred in the group that had open repair. Seven complications (12%) including vessel injury and early recurrence arose in the group that had laparoscopic repair (difference in complication rate 10% (95% confidence interval 4% to 18%; P = 0.02). Pain scores and quality of life assessed by the short form 36 showed a significant benefit to the group that had laparoscopic repair in the early postoperative period. Return to normal activity was not significantly different between the two groups. Total theatre costs were higher in the group that had laparoscopic repair (mean cost for laparoscopic repair 850 pounds (622 pounds to 1078 pounds); mean cost for open repair 268 pounds (245 pounds to 292 pounds)). CONCLUSIONS: Because of the greater complication rate and higher theatre costs for laparoscopic repair and the patient outcome preferences expressed, the results of larger trials of clinical and cost effectiveness using recurrence as the primary outcome measure should be known before laparoscopic herniorrhaphy is widely adopted.

Adult↗
PubMed1995

Sensitivity to change of health status measures in a randomized controlled trial: comparison of the COOP charts and the SF-36.

This study compared the sensitivity to change of comparable dimensions of a multi-item multi-dimensional health status measure (the SF-36) with the equivalent single item domains on the Dartmouth COOP charts. One hundred and twenty nine patients were randomized to either day case laparoscopic surgery (n = 60) or open inguinal hernia repair (n = 69). Respondents completed the SF-36 and COOP charts at baseline (prior to surgery) and at follow up at 10 days and 6 weeks. Equivalent dimensions of physical functioning, mental health/emotional condition, social activities, pain and overall condition/general health on the two questionnaires were compared. Despite slightly different pictures of change provided by the physical functioning and 'overall condition/general health' dimensions the general picture of change provided by the two instruments was similar. At 10 days, patients who underwent open surgery reported far greater levels of dysfunction than those who underwent laparoscopic surgery on both questionnaires. At 6 weeks the pain dimension of both questionnaires indicated a large improvement from baseline, whilst no other domain on either questionnaire for either group indicated such improvement. The general picture of change provided by the two measures was similar. The results suggest that both the SF-36 and the COOP charts may prove suitable for the assessment of health perception outcomes in surgical clinical trials. Differences on certain domains were caused in large measure by the nature of the questions posed. The study once again highlights the importance of checking item content to determine the suitability of any particular measure for a given study.

Adult↗
PubMed1994

Role of vif during packing of the core of HIV-1.

The viral infectivity factor gene vif of human immunodeficiency virus type 1 (HIV-1) has been shown to enhance the cell-free infectivity of HIV-1 virus particles. Previous studies have demonstrated that vif increases viral infectivity at the time of virus production, most likely by affecting viral protein processing, virus assembly, or virus maturation. The effect of vif on the assembly and maturation of HIV-1 propagated in CEM, Jurkat, and SupT1 cells was examined by electron microscopy and goniometer analysis. CEM and Jurkat cells are nonpermissive and partially permissive for the replication of vif--defective viruses, respectively, while SupT1 cells are completely permissive. In CEM and Jurkat cultures, the morphology of immature vif+ and vif- virions was similar but immature virus particles were observed at a slightly higher frequency in cultures infected with the vif- virus. At later stages of virus maturation, however, nonhomogeneous packing of the core was detected in the majority of vif- virus particles produced in CEM and Jurkat cells. In the absence of vif, the cone-shaped virus core contained dense material in its broad end but, in contrast to vif+ virions, the material inside its narrow end appeared transparent. The narrow part of the vif- virus core was surrounded by a shell and was attached to the viral envelope by a core-envelope link structure. Vif- virus particles with a lateral body of core material adjacent to the viral envelope were also observed more frequently in CEM and Jurkat cultures. In contrast, in SupT1 cultures the morphology of mature vif+ and vif- virus particles was similar. These results suggest that vif is associated with an effect during the final stages of packing of the viral nucleoprotein core. This effect may be important for the infectivity of HIV-1 virus particles.

Cell Line↗
PubMed1994

Permittivities of fresh fruits and vegetables at 0.2 to 20 GHz.

Permittivities, moisture contents, tissue densities, and total soluble solids data were determined for samples of twenty-three kinds of fresh fruits and vegetables at 23 degrees C. Permittivities were measured at 41 frequencies between 200 MHz and 20 GHz with an open-ended coaxial-line probe and a microwave network analyzer. Results of the permittivity measurements are presented graphically, and dielectric constant and loss factor values at six frequencies across the range are tabulated along with sample descriptions and moisture, density, and total soluble solids data. Although specific values differ, the dielectric constant decreases steadily with increasing frequency, dropping more rapidly at frequencies above 5 GHz. Values for the loss factor decrease as frequency increases above 200 MHz to a broad minimum in the 1- to 3-GHz region and then increase again as the frequency approaches 20 GHz. The dielectric behavior of the fruit and vegetable tissues appears to be influenced by ionic conductivity and bound water relaxations at the lower frequencies and by free water relaxation at the higher end of the frequency range.

Fruit↗