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

Mark Linzer, Catherine Pierce, Elizabeth Lincoln, Donald R. Miller, Susan M. Payne, Jack A. Clark, Katherine M. Skinner, Sheldon Greenfield, Sherrie Kaplan, Colleen A. McHorney, Austin Lee, Lewis E. Kazis

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

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 ischemice 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 R22 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.

Original languageEnglish (US)
Pages (from-to)167-176
Number of pages10
JournalJournal of Ambulatory Care Management
Volume28
Issue number2
DOIs
StatePublished - 2005

Keywords

  • Case mix
  • Diabetes
  • Outcomes
  • Quality of life
  • Risk adjustment
  • Severity of illness

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