Biomedical subjects

Jack A Clark

Publications and source records attributed to Jack A Clark.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Preliminary validation of a patient-based self-assessment measure of severity of illness in type 2 diabetes: results from the pilot phase of the Veterans Health Study.

Measures of case mix are needed to control for patients' clinical status in studies assessing the process and outcomes of care. The Veterans Health Study (VHS) is a longitudinal study of determinants of health outcomes in ambulatory veterans. This study assessed the validity of a case-mix measure developed to quantify severity of illness in ambulatory type 2 diabetic patients. As part of the pilot phase of the VHS, 245 veterans using 4 primary care clinics in Boston were screened for diabetes and 5 other chronic illnesses when they presented for care. Subjects screening positive for diabetes returned to complete severity of illness and outcome measures. The variables for the diabetes case-mix module were chosen based upon the principles of parsimony, duration of follow-up, and clinical validity and credibility. Variables were selected to predict function, as measured by the Medical Outcomes Study Short-Form 36 (SF-36). The diabetic patients in this study had a heavy burden of chronic illness, with an average of 3.9 comorbid conditions and a mean general health perceptions score of 48 on the SF-36 (scored from 0 to 100, with 100 indicating best health). A summary variable called DMSEV was created for "diabetes severity". This included atherosclerotic complications(stroke, transient ischemic attack or myocardial infarction; chest pain frequency; and claudication), plus any history of eye, foot, or neuropathic symptoms. DMSEV correlated with all 8 outcome scales of the SF-36, and in particular was highly associated with physical function (r=0.49, P=.0001). Least squares linear regression analysis controlling for age and comorbidity confirmed the association of DMSEV with all 8 SF-36 scales. The correlation with physical function remained highly significant (P<.0001), with an R of 0.31. This patient-based self-assessment questionnaire and the summary variable DMSEV appear to be valid measures of severity of illness in ambulatory diabetic veterans with multiple comorbidities. After further testing, this case-mix measure may be suitable for controlling for severity of illness in ambulatory-based studies of diabetic patients with multiple chronic illnesses.

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PubMedDate not supplied

Assessment of long-term complications due to type 2 diabetes using patient self-report: the diabetes complications index.

This study aims to develop a patient-based measure of the complications of type 2 diabetes that can be used in examining its relationship with health-related quality of life (HRQOL) and utilization of health services. Using questions analogous to those typically employed by clinicians, we developed a 17-item questionnaire to identify prior diagnoses and current symptoms of 6 common complications of type 2 diabetes. We administered it to 419 patients with type 2 diabetes who were part of the Veterans Health Study, a larger prospective investigation of veterans receiving ambulatory care. From the responses, we calculated a simple sum of the 6 complications. We examined the correlation of this Diabetes Complications Index (DCI) with use of diabetes-related medical resources, outpatient doctor visits, HRQOL, duration of diabetes, and the degree to which patients perceived their health to be diminished by diabetes. The DCI was significantly correlated with the degree to which patients perceived their health to be diminished by diabetes (r = 0.35, P = .0001), utilization of diabetes-related resources (model R = 0.15, P = .0001), outpatient doctor visits (model R = .08, P = .001), and duration of diabetes (r = 0.11, P = .04). It had a good correlation with aspects of HRQOL that reflect physical function when controlling for age and comorbid conditions (model R = 0.23, P = .0001). The DCI shows promise as an efficient method for assessing the effects of type 2 diabetes on HRQOL and predicting utilization of medical resources.

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PubMedDate not supplied

Patient-based measures of illness severity in the Veterans Health Study.

The Veterans Health Study (VHS) was designed to produce patient-based measures of health status suitable for monitoring the health of men served by the Veterans Health Administration. This article summarizes the objectives, conceptual framework, and results of 6 substudies of the VHS that were designed to develop disease-focused measures of illness severity, that is, patient-perceived, clinically significant manifestations of disease processes that are associated with decrements in health-related quality of life. Developmental psychometric studies used cross-sectional survey data from the baseline comprehensive evaluations conducted in the VHS. Patients who screened positive for the 6 study medical conditions in the VHS (osteoarthritis of the knee, n = 511; type 2 diabetes, n = 425; chronic lung disease, n = 352; hypertension, n = 996; chronic low-back pain, n = 574; and alcohol-related disorder, n = 175) were administered structured interview modules that assessed symptoms and complications of these chronic diseases. Psychometric analyses were conducted to identify internally coherent and reliable indices, which were validated with respect to their correlations with measures of health-related quality of life (eg, Short Form-36) and the utilization of health services. We constructed 6 indices of illness severity. The severities of osteoarthritis of the knee and chronic lung disease were defined by brief (12 and 6 items, respectively) assessments of symptoms (eg, knee pain and dyspnea). Since diabetes and hypertension are largely asymptomatic, illness severity for these conditions was assessed by ascertaining complications such as angina and vascular disorders. Alcohol-related disorder, which involves both behavioral symptoms and physical complications, was assessed by separate scales for these 2 dimensions of its severity. Chronic low-back pain required a unique solution. Rather than assessing the intensity of back pain, it is more productive to construct a measure that focuses on manifestations of radiculopathy, that is, whether back pain radiated down the leg to below the knee. The 5 symptoms or complication indices and the assessment of radiculopathy in chronic low-back pain were significantly correlated with Short Form-36 scores and intensity of recent use of health services. The 6 measures may complement measures of health-related quality of life in providing more comprehensive assessments of health status in Veterans Affairs patients.

Chronic Disease↗

PubMedDate not supplied

Applications of methodologies of the Veterans Health Study in the VA healthcare system: conclusions and summary.

The Veterans Health Study (VHS) had as its overarching goal the development, testing, and application of patient-centered assessments for monitoring patient outcomes in ambulatory care in large integrated care systems such as the Department of Veterans Affairs (VA). Unlike other previous studies, the VHS has capitalized on rich administrative databases restricted to the VA and linked to patient-centered outcomes. The VHS has developed a comprehensive set of general and disease-specific measures for use by systems of care for ambulatory patients. Chief among these assessments is the Veterans SF-36 Health Survey for measuring health-related quality of life in veteran ambulatory populations. The Veterans SF-36 Health Survey provides the cornerstone for this study and historically has been extensively disseminated and used in the VA with close to 2 million administrations nationally as part of its quality management system. National surveys administered by the VA since 1996 using the Veterans SF-36 Health Survey indicate important regional differences with implications for varying resource needs. Based upon the rich foundation provided by the VHS methodology, the VA has implemented some of these approaches as part of its quality monitoring system and can serve as a model for other large integrated systems of care.

Delivery of Health Care↗