Regional variation in health status among chronic obstructive pulmonary disease patients.

BACKGROUND: Little is known about geographic differences in health status among patients with chronic obstructive pulmonary disease (COPD).
OBJECTIVES: The aim of this study was to examine regional variations in self-reported health status of COPD patients at 7 Veterans Affairs clinics.
METHODS: The Ambulatory Care Quality Improvement Project was a multicenter, randomized trial conducted from 1997 to 2000 that evaluated a quality improvement intervention in the primary care setting. Four thousand and nine participants with COPD (age ≥45 years) completed the Seattle Obstructive Lung Disease Questionnaire (SOLDQ) and 2,991 also completed the Medical Outcomes Study 36-item short form (SF-36). The unadjusted maximal difference in health status scores is reported as the ratio of the highest and lowest site prevalence. We report the maximal site difference in mean health status scores after adjusting for demographics, comorbidities, utilization, medication use and clinic factors.
RESULTS: Subjects were predominantly older (66.5 ± 9.2 years) Caucasian (83.2%) men (97.9%). After adjustment, the maximal site difference for each health status score was significant (p < 0.01) but larger for the SOLDQ (physical 11.2, emotional 9.7, coping skills 7.6) than for the SF-36 (physical component summary 4.7, mental component summary 2.6). Most of the health status variation was explained by individual or clinic level factors, not clinic site.
CONCLUSIONS: Our models explained <30% of variation in health status measures; therefore, future studies should consider additional predictors of health status such as physical performance, social determinants of health, COPD treatment and environmental factors. Despite its limitations, this study suggests a need to consider regional differences in health status when comparing COPD health outcomes in diverse geographic areas.