Search PubMed⌕ Search

Biomedical subjects

M M Ward

Publications and source records attributed to M M Ward.

At least 73 records · Page 4Linked to original sources
PubMed1995

Physical disability in older runners: prevalence, risk factors, and progression with age.

BACKGROUND: Concern exists that certain types of exercise, particularly vigorous activity, may increase physical disability among older individuals. We investigated the prevalence of, and risk factors for, physical disability in active older persons (runners), and examined factors influencing the progression of physical disability with age. METHODS: Physical disability, measured using the Health Assessment Questionnaire Disability Index, was assessed prospectively in 454 runners, age 50 or greater, over five to seven years by annual mailed questionnaires. Baseline sociodemographic, clinical, and life-style characteristics associated with the presence of any disability over the course of the study were determined and contrasted with those in 292 older non-runners who had been similarly followed. RESULTS: Two hundred twenty-two runners (49%) reported some physical disability during the study. The presence of arthritis symptoms at baseline was the most important risk factor for physical disability; older age, greater body mass index, strenuous work-related physical activity, and the use of more medications were also associated with a greater likelihood of physical disability. Among the non-runners, 224 (77%) reported some physical disability, and the presence of arthritis symptoms was also the most important risk factor for physical disability in this group. Age-related changes in physical disability differed between those with and without arthritis symptoms in both the runner and non-runner groups. CONCLUSIONS: The presence of arthritis symptoms was an important risk factor for physical disability among both older runners and non-runners, and also identified subgroups of individuals with different progressions of disability with age.

Age Factors↗
PubMed1995

Interruptions in rheumatology subspecialty care among patients with rheumatoid arthritis.

OBJECTIVE: To identify factors associated with interruptions in care from rheumatologists among patients with rheumatoid arthritis (RA). METHODS: A person-time analysis was used to examine the association of medical insurance status, income, health status, treatment by a primary care physician, and presence of comorbid conditions with interruptions in rheumatology subspecialty care in a cohort of 161 patients with RA followed prospectively for up to 10 years. An interruption was defined as a 6-month period during which a patient was not treated by a rheumatologist. Each patient had at least one interruption. RESULTS: Interruptions in rheumatology care occurred more commonly during periods when patients reported no medical insurance coverage than when they had medical insurance coverage (relative risk, RR = 1.49; 95% confidence interval, CI = 1.05, 2.11). Interruptions in care were more common during intervals in which patients reported at least a 40% improvement in functional disability (RR = 1.30; 95% CI = 1.03, 1.63), but interruptions were not associated with either absolute or relative changes in pain or global arthritis status. Interruptions in rheumatology care also occurred more commonly during periods when patients reported seeing a primary care physician (RR = 2.07; 95% CI = 1.71, 2.50), and when they reported having a comorbid condition (RR = 1.37; 95% CI = 1.06, 1.77). Income was not associated with interruptions in care. CONCLUSION: Lack of medical insurance and short term improvements in functional disability are associated with interruptions in rheumatology care among patients with RA. Patients also appear to substitute primary care for care from rheumatologists. These associations suggest that potential strategies for enhancing continuity in rheumatology care might include the promotion of universal insurance coverage and the development of informational programs for patients.

Adult↗
PubMed1994

Serial measurement of serum interleukin-2 receptor levels in patients with rheumatoid arthritis: limited evidence for a role of T cell activation in clinical exacerbations.

To investigate the association of T cell activation with clinical exacerbations of RA, we measured serum levels of soluble interleukin-2 receptors (sIL2R), a marker of T cell activation, in serial samples obtained from 23 patients with RA. sIL2R measurements were performed on sera obtained from each patient every 2 weeks for up to 60 weeks, and levels were correlated with swollen joint counts, tender joint counts, physician global assessments, patient global assessments, pain scores, Health Assessment Questionnaire Disability Index scores, and Westergren erythrocyte sedimentation rates measured simultaneously. There were no significant correlations between changes in sIL2R levels and changes in any of the other measures, nor were lead-lag relationships detected, for the group as a whole. Examination of the time courses of individual patients revealed significant positive correlations between changes in sIL2R levels and changes in swollen joint counts in five patients; significant correlations with other measures were present in three or fewer patients. sIL2R levels also varied little over the 2-week time interval of greatest clinical change in each patient. These results suggest either that clinical exacerbations of RA are not associated with changes in T cell activation or that sIL2R levels do not accurately reflect such changes.

Adult↗
PubMed1994

Effect of smoking cessation and relapse on cardiovascular levels and reactivity.

This study was designed to investigate the effect of smoking cessation on heart rate, blood pressure, and finger temperature absolute levels and reactivity to a range of laboratory challenges. The 148 quitters (mean age = 43.3 years, mean amount smoked = 24.9 cigarettes per day, mean years smoked = 25.2) completed three assessments: an average of 4 +/- 2.8 days before cessation (Exam 1), an average of 2 +/- 1.0 days after cessation (Exam 2), and an average of 20 +/- 5.5 days after cessation (Exam 3). A nonsmoking group (n = 39) was similarly assessed three times to control for effects related to repeated testing. Comparison of group changes from Exam 1 to Exam 2 indicated that smoking cessation produced a significant decrease in heart rate during rest and during all stressors (mean = -8.9 bpm). Those quitters who remained abstinent or smoked occasionally showed minimal changes in heart rate from Exam 2 to Exam 3, but those quitters who returned to their previous smoking level showed a significant increase in heart rate from Exam 2 to Exam 3. None of the indices of cardiovascular reactivity changed across exams, and neither did absolute levels of blood pressure or finger temperature at rest or during stressors. The possible mechanisms producing a selective heart rate decline after smoking cessation in the absence of pressor or vasodilation effects are discussed.

Adult↗
PubMed1994

Clinical measures in rheumatoid arthritis: which are most useful in assessing patients?

OBJECTIVE: To determine the relative accuracy and sensitivity to change of 14 measures commonly used to assess arthritis activity in patients with rheumatoid arthritis (RA). METHODS: Twenty-four patients with RA were prospectively examined every 2 weeks for up to 60 weeks. At each examination, arthritis activity was assessed using 5 physician determined measures (global assessment, swollen joint count, weighted swollen joint count, tender count, weighted tender joint count), 3 patient determined measures (global assessment, pain score, duration of morning stiffness), 3 functional measures (Health Assessment Questionnaire Disability Index, grip strength, 50' walk time), and 3 laboratory measures [Westergren erythrocyte sedimentation rate (ESR), hemoglobin, platelet count]. Accuracy was determined by the degree to which changes in each measure over time were related to changes in other measures (i.e., correlational validity). Sensitivity to change was measured using standardized response means. RESULTS: Over the course of the study, each patient had at least 6 measures change more than 50% from their baseline values. The most highly intercorrelated measures were the physician global assessment (range of partial correlations r = 0.4-0.7), patient global assessment and pain scores (r = 0.2-0.7), the Disability Index (r = 0.3-0.7), and ESR (r = 0.2-0.4). Physician and patient global assessments, pain scores, and the Disability Index were more sensitive to change than other measures, while laboratory measures were generally less sensitive to change. CONCLUSION: Based on the relative accuracy and sensitivity to change of these 14 clinical measures, the physician global assessment, a functional status questionnaire, and the patient global assessment or pain score should be the principal measures used to assess arthritis activity in patients with RA. Recognizing its limitations, the ESR could be included if a laboratory measure is needed.

Adult↗
PubMed1994

Are patient self-report measures of arthritis activity confounded by mood? A longitudinal study of patients with rheumatoid arthritis.

OBJECTIVE: To determine the extent to which mood in general, and depression in particular, may confound self-report measures of functional disability, pain, and global arthritis status among patients with rheumatoid arthritis (RA). METHODS: Twenty-four patients with RA were prospectively examined every 2 weeks for up to 60 weeks. At each examination, self-report measures of functional disability, pain, and global arthritis status were assessed using the Health Assessment Questionnaire, and the clinical measures of swollen and tender joint counts, duration of morning stiffness, grip strength, 50' walk time, and Westergren sedimentation rate were recorded. In addition, patients completed a questionnaire derived from the Profile of Mood States-B (POMS-B), which assessed positive and negative moods, and the Center for Epidemiologic Studies Depression Scale (CES-D) at each examination. The degree to which mood or depression confounded the self-report measures of functional disability, pain, and global arthritis status was estimated using pooled time series regression models that examined the relationship between changes in either mood or depression and changes in each self-report measure over the course of the study, while controlling for the effects of the clinical measures of arthritis activity. RESULTS: Mood, as measured by the POMS-B scale, explained 2.0% or less of the variation in longitudinal changes in each of the self-report measures, after controlling for the effects of the clinical measures of arthritis activity. Depression, as measured by the CES-D, explained less than 2.0% of the variation in changes in functional disability, but explained 6.0 and 8.0% of the variation in changes in pain and global arthritis status, respectively. CONCLUSION: Depression may confound self-reports of pain and global arthritis status somewhat, but appears to have minimal influence on self-reported functional disability.

Adult↗
PubMed1993

Progression of functional disability in patients with rheumatoid arthritis. Associations with rheumatology subspecialty care.

BACKGROUND: To determine whether patients with rheumatoid arthritis and their physicians make appropriate decisions regarding referral to rheumatologists and the need for continuing rheumatology care, we examined the relationship between the progression of functional disability in these patients and their use of rheumatology subspecialty care over time. METHODS: A cohort of 282 patients with rheumatoid arthritis was followed prospectively for up to 10 years. Participants were categorized into three subgroups based on the pattern of care received from rheumatologists over the study period: patients who were never treated by a rheumatologist; patients treated by a rheumatologist only intermittently; and patients treated by a rheumatologist at least once during each 6-month study period. The outcome was the rate of progression of functional disability, measured using the Health Assessment Questionnaire Disability Index. RESULTS: Among the 52 patients who had not been referred to a rheumatologist, 30 (58%) had rates of progression of functional disability that were stable or improving over time (rate < 0.01 Disability Index units per year), while 22 (42%) had rates that were worsening (rate > or = 0.01 Disability Index units per year). Among patients treated by rheumatologists, the average rate of progression was substantially lower among the 69 patients who were treated regularly by a rheumatologist than among 161 patients treated by rheumatologists intermittently (0.008 Disability Index units per year vs 0.020 Disability Index units per year). This difference was associated with more intensive use of second-line antirheumatic medications, and more frequent joint surgeries, among patients treated by rheumatologists on a regular basis. CONCLUSIONS: Most patients with rheumatoid arthritis in this community cohort were treated by a rheumatologist, but 42% of those not referred had progressively increasing functional disability. Among patients treated by rheumatologists, those who had continuing care from rheumatologists experienced lower rates of progression of functional disability than those who had only intermittent care. These results suggest that use of rheumatology subspecialty care is associated with better health outcomes in rheumatoid arthritis.

Activities of Daily Living↗
PubMed1993

Reducing attrition bias with an instrumental variable in a regression model: results from a panel of rheumatoid arthritis patients.

This study proposes an econometric technique to reduce attrition bias in panel data. In the simplest case, one estimates two regressions. The first is a probit regression based on sociodemographic and clinical characteristics measured at baseline. The probit regression estimates the probability that subjects stay or leave over the duration of the study. We insert the predicted probabilities from the probit regression into an inverse Mills ratio (IMR) or hazard rate to form an instrumental variable. We use this instrumental variable subsequently as an additional covariate in a second regression model that attempts to explain fluctuations in the dependent variable. The second regression, which is linear, includes only subjects who remained in the study. In alternative models, instrumental variables are created using predicted values from least squares and logit regressions estimating the probability that subjects stay or leave. The use of the instrumental variables reduces the effects of attrition bias in the linear regression model. We applied the technique to a panel of patients with rheumatoid arthritis (RA) enrolled in 1981 and followed through 1990. We attempted to predict values for a measure of functional disability recorded in 1990 with use of covariates measured in 1981. The dependent variable was an index of disability in 1990 and the independent variables (covariates) included the disability index from 1981, the years of duration of RA, gender, marital status, education, and age in 1981. The correction technique suggested that ignoring attrition bias would underestimate the strength of associations between being female and the subsequent disability index, and overestimate the strength of associations between being married spouse present, age, and the initial disability index on the one hand and the subsequent disability index on the other.

Age Factors↗
PubMed1993

Marital status and the progression of functional disability in patients with rheumatoid arthritis.

OBJECTIVE: To determine if marital status is associated with differences in rates of progression of functional disability in patients with rheumatoid arthritis (RA). METHODS: A community cohort of 282 persons with RA was followed prospectively for up to 9.5 years. The progression of functional disability over time was determined using the Health Assessment Questionnaire Disability Index, which was completed by study participants every 6 months. RESULTS: At study entry, the Disability Index was 1.1 +/- 0.8 (mean +/- 1 SD) (possible range 0-3) among the 188 married participants and 1.3 +/- 0.9 among the 94 unmarried participants. Over time, the rate of progression of functional disability was generally higher among unmarried participants. However, the extent of this difference varied somewhat over the disease course, with rates of progression higher among unmarried than among married participants during years 5-7 and years 17-29 of RA. Overall estimated rates of progression, adjusted for the effects of other sociodemographic factors, were 0.03 Disability Index units per year in unmarried participants and 0.01 Disability Index units per year in married participants (P < 0.0001). CONCLUSION: Marriage, possibly reflecting the influence of social support, is associated with a lower rate of progression of functional disability in persons with RA.

Adult↗
PubMed1993

Pooled time series regression analysis in longitudinal studies.

Many longitudinal studies attempt to examine changes in outcome measures over time in groups of patients. Applying conventional analytic techniques, such as a single classical linear regression model, to these data will often not result in minimum variance estimates, and may affect the results of tests of significance. Pooled time series regression analyses comprise a set of techniques that may be used in these instances to model changes in outcome measures over time. Pooling of time series data from many individuals may be done using two types of models: fixed effect models, which specify differences among individuals in separate intercept terms, and random effects models, which allow for differences among individuals by including an additional error component in the model. The choice between these alternative model specifications is guided by both theoretical and statistical considerations. This paper describes the use of pooled time series analysis, contrasts these methods with two classical linear regression approaches, and demonstrates these differences using two examples: a hypothetical study of serum glucose measurements in patients with diabetic ketoacidosis, and a longitudinal study of the development of functional disability in a cohort of patients with rheumatoid arthritis. These methods may be applicable to the study of outcomes in many chronic illnesses.

Humans↗
PubMed1993

Differential rates of relapse in subgroups of male and female smokers.

Subjects for this study were 265 participants of stop-smoking clinics (mean age = 42.6 years; average number of cigarettes smoked daily = 26.0) who were examined before and immediately after cessation and then followed for 1 year. The objective of this study was to identify subgroups of smokers with different rates of relapse using tree-structured survival analysis, a multivariate approach to classification. Five distinct subgroups that differed with respect to the rate of relapse were identified: (I) subjects (n = 15) with very low precessation cotinine levels (< or = 129 ng/ml), who had an exceptionally low rate of relapse (mean abstinence time = 270 days); (II) women 32 years old and younger (n = 24), who had a very high rate of relapse (mean abstinence time = 30.5 days); (III) women over 32 years old (n = 121), with the next highest rate of relapse (mean abstinence time = 98.9 days); (IV) men 36 years old and younger (n = 31), who had a mean abstinence time of 196.7 days; and (V) men over 36 years old (n = 74), who abstained an average of 130.2 days before relapsing. Relapse curves for all groups (except III vs V) differed significantly from each other, p < 0.05. Results indicate that this approach can identify interactions among individual differences that are variably associated with relapse rates. Identification of relapse subgroups may have important implications for both theories and treatment of smoking relapse.

Adult↗
PubMed1993

Cardiovascular reactivity as a predictor of relapse in male and female smokers.

This study examined the role of psychophysiological reactivity to general stressors measured before smoking cessation as a predictor of relapse in individuals who quit for a minimum of 12 hr and were then followed for a 12-month interval. The study group consisted of 132 (56.9%) female and 100 (43.1%) male participants in a formal smoking cessation program. The reactivity measures were taken while the Ss were still smoking. Heart rate and blood pressure measurements were taken while Ss were resting, performing mental arithmetic, and delivering a speech and after Ss had been standing for 2 min. In the sample as a whole and for women, a higher level of systolic blood pressure reactivity to the cognitive challenge was associated with a shorter time to relapse (p < .05). In men, greater systolic blood pressure decline to standing was significantly associated with a shorter time to relapse (p < .05).

Adult↗
PubMed1993

The relative importance of pain and functional disability to patients with rheumatoid arthritis.

OBJECTIVE: Pain and functional disability are 2 major factors influencing the health status of patients with rheumatoid arthritis (RA). To determine the relative importance ascribed to these factors by patients, we examined the relationship of levels of both pain and functional disability to self-reported global arthritis status in patients with RA. METHODS: Pain, disability and global arthritis status were measured prospectively in 305 patients with RA using the Health Assessment Questionnaire, which was completed by patients every 6 months for up to 9.5 years. The relative importance of pain and functional disability was determined by the relative magnitude of their association with global arthritis status, as estimated by pooled time series regression analysis. RESULTS: At study entry, median levels of pain, functional disability, and global arthritis status for the cohort were 1.1 (possible range: 0-3.0), 1.25 (possible range: 0-3.0), and 35 (possible range: 0-100), respectively, indicating moderate arthritis severity. Both pain (p < 0.0001) and functional disability (p < 0.0001) were significantly related to changes in global arthritis status over time. The standardized regression coefficient of pain was 1.2 times larger than that of disability, indicating that patients' ratings of their arthritis status was only slightly more heavily weighted by changes in pain than by changes in functional disability. Pain was a more important feature than disability among nonwhites (pain/disability standardized coefficient ratio = 2.7), while disability appeared to be more important for males (ratio = 0.8). The duration of RA did not influence the relative importance of pain and disability. CONCLUSION: Pain and functional disability were of similar importance to this group of patients with RA, and the relative importance of pain and disability did not vary with the duration of RA.

Adult↗
PubMed1992

A nontoxic, idiotope vaccine against gram-negative bacterial infections.

Experiments were performed to test the ability of mouse antiidiotopic mAb, specific for an antilipid A mAb, to act as a vaccine against gram-negative bacterial infections. Lipid A is a conserved region of bacterial LPS. Immunization with the antiidiotopic antibodies, coupled to an immunogenic carrier protein (hemocyanin), specifically induced anti-LPS antibody responses in animals from different species. In a mouse model, this immunization resulted in protection against both lethal gram-negative bacteremia and endotoxemia. The antiidiotopic antibodies, however, did not stimulate endotoxin-associated bioactivities, such as induction of TNF and IL-1. These results support the hypothesis that an idiotope vaccine can stimulate beneficial protective immunity against gram-negative infections without the toxicity inherent in LPS.

Animals↗
PubMed1992

Patterns of heavy and light chain utilization in the antibody response to single-stranded bacterial DNA in normal human subjects and patients with systemic lupus erythematosus.

Although anti-DNA antibodies are generally considered to be specific markers for systemic lupus erythematosus (SLE), antibodies binding DNA from certain bacterial species can be found in the sera of normal subjects. To characterize the immunochemical properties of these antibodies, the IgG subclass and light chain profile of antibodies to single-stranded micrococcal DNA (MC DNA) in the sera of normal subjects and patients with SLE was determined. The anti-MC DNA response in normal sera was predominantly of the IgG2 subclass with a marked predominance of kappa light chains. In contrast, anti-MC DNA antibodies in SLE sera exhibited all IgG subclasses with a predominance of the IgG1 subclass and both kappa and lambda light chains were represented. These results suggest that antibodies to bacterial DNA in the sera of normal subjects and patients with SLE differ in patterns of immunoglobulin gene expression; the restricted response of normal subjects may be related to the binding to a discrete DNA determinant.

Antibody Formation↗
PubMed1992

Clinical prognostic factors in lupus nephritis. The importance of hypertension and smoking.

BACKGROUND: Many previous studies of the influence of sociodemographic and clinical factors on the development of renal failure in patients with lupus nephritis have been based on selected subgroups of patients and have yielded conflicting results. We sought to determine the prognostic importance of patient demographic characteristics (age, gender, race, and socioeconomic status), smoking status, and hypertension in the development of end-stage renal disease (ESRD) among patients with lupus nephritis. METHODS: This retrospective cohort study followed an inception cohort of 160 adults with lupus nephritis. The outcome measure was the development of ESRD, defined as the institution of maintenance dialysis or measurement of a creatinine clearance of 10 mL/min or less. Life-table analysis was used to determine differences between patient subgroups in the time to development of ESRD. RESULTS: End-stage renal disease developed in 41 (26%) of 160 patients followed up for a median of 6.4 years. Hypertension and smoking status at the onset of nephritis were strongly associated with differences in the time to development of ESRD. The median time to ESRD among patients with moderate to severe hypertension (diastolic blood pressure, greater than or equal to 105 mm Hg) was 7 months, among patients with mild hypertension (diastolic blood pressure, 90 to 104 mm Hg) it was 146 months, and among normotensive patients it was greater than 273 months. The median time to ESRD among smokers was 145 months and among nonsmokers it was greater than 273 months. These effects persisted in multivariable analyses adjusting for differences among patients in age, gender, socioeconomic status, renal histology, and immunosuppressive treatment. The independent effects of hypertension and smoking resulted in shorter times to renal failure among patients who were both hypertensive and smoking, compared with nonsmoking hypertensive patients. The development of ESRD did not differ among patient demographic subgroups. CONCLUSION: Patient demographic characteristics had no detectable impact on the rate of progression to ESRD in this cohort. Hypertension and smoking appear to be important, potentially modifiable, factors influencing the prognosis of patients with lupus nephritis.

Adult↗
PubMed1991

The primary B cell response to the O/core region of bacterial lipopolysaccharide is restricted to the Ly-1 lineage.

Experiments were performed to test the hypothesis that Ly-1 B cells respond to antigenic challenge with LPS from gram-negative bacteria. To perform these experiments, the splenic fragment culture system for the study of B cell precursors was used. We found that a significant number of anti-O/core, but not anti-lipid A, precursors expressed the lambda L chain. A restriction of the anti-LPS response to Ly-1 B cells was tested using a Ly-1 depletion protocol. We found that the anti-O/core antibody response was restricted to the Ly-1 B cell lineage. In contrast, conventional B cells, not Ly-1 B cells, respond to an antigenic challenge with lipid A. Our results further support the idea that the Ly-1 B cell lineage serves a direct role in protecting against certain bacterial infections.

Animals↗