Using quality of life to predict hospitalization and mortality in patients with obstructive lung diseases

Abstract

Study objectives: Condition-specific measures of quality of life (QOL) for patients with COPD have been demonstrated to be highly reliable and valid, but they have not conclusively been shown to predict hospitalization or death.

Objective: We sought to determine whether a brief, self-administered, COPD-specific QOL measure, the Seattle Obstructive Lung Disease Questionnaire (SOLDQ), could accurately predict hospitalizations and death.

Design: Prospective cohort study.

Setting: Patients enrolled in the primary care clinics at seven Department of Veterans Affairs (VA) medical centers participating in the Ambulatory Care Quality Improvement Project.

Patients: Of 24,458 patients who completed a health inventory, 5,503 reported having chronic lung disease. The 3,282 patients who completed the baseline SOLDQ were followed for 12 months.

Measurements: Hospitalization and all-cause mortality during the 1-year follow-up period.

Results: During the follow-up period, 601 patients (18.3%) were hospitalized, 141 (4.3%) for COPD exacerbations, and 167 patients (5.1%) died. After adjusting for age, VA hospital site, distance to the VA hospital, employment status, and smoking status, the relative risk of any hospitalization among patients with scores on the emotional, physical, and coping skills scales of the SOLDQ that were in the lowest quartile, when compared to the highest quartile, were 2.0 (95% confidence interval [CI], 1.5 to 2.6), 2.5 (95% CI, 1.9 to 3.4), and 1.9 (95% CI, 1.5 to 2.5), respectively. When hospitalizations were restricted to those specifically for COPD, the odds ratio (OR) for the lowest quartile of physical function was 6.0 (95% CI, 3.1 to 11.5). Similarly, patients in the lowest quartile of physical function also had an increased risk of death (OR, 6.8; 95% CI, 3.3 to 13.8). When adjusted for comorbidity (OR, 0.8; 95% CI, 0.5 to 1.2), long-term steroid use (OR, 2.8; 95% CI, 1.6 to 4.9), and prior hospitalization for COPD (OR, 4.5; 95% CI, 2.2 to 9.2), patients having baseline SOLDQ physical function scores in the lowest quartile had an odds of hospitalization for COPD that was fivefold higher than patients with scores in the highest quartile (OR, 5.0; 95% CI, 2.6 to 9.7).

Conclusions: Lower QOL is a powerful predictor of hospitalization and all-cause mortality. Brief, self-administered instruments such as the SOLDQ may provide an opportunity to identify patients who could benefit from preventive interventions.