Limited lung function: impact of reduced peak expiratory flow on health status, health-care utilization, and expected survival in older adults

Abstract

The authors examined whether peak expiratory flow (PEF) is a valid measure of health status in older adults. Survey and test data from the 2006 and 2008 cycles of the Health and Retirement Study, a longitudinal study of US adults over age 50 years (with biennial surveys initiated in 1992), were used to develop predicted PEF regression models and to examine relations between low PEF values and other clinical factors. Low PEF (<80% of predicted value) was prevalent among persons with chronic conditions, including frequent pain, obstructive lung disease, heart disease, diabetes, and psychological distress. Persons with higher physical disability scores had substantially higher adjusted odds of having low PEF, on par with those for conditions known to be associated with poor health (cancer, heart disease, and stroke). In a multivariate regression model for difficulty with mobility, PEF remained an independent factor (odds ratio (OR) = 1.69, 95% confidence interval (CI): 1.53, 1.86). Persons with low PEF in 2006 were more likely to be hospitalized (OR = 1.26, 95% CI: 1.10, 1.43) within the subsequent 2 years and to estimate their chances of surviving for 10 or more years at less than 50% (OR = 1.69, 95% CI: 1.24, 2.30). PEF is a valid measure of health status in older persons, and low PEF is an independent predictor of hospitalization and poor subjective mortality assessment.

Figure 1.

Adjusted odds ratio for reduced lung function (<80% of predicted peak expiratory flow (PEF)) according to chronic diseases and demographic factors among respondents who had more than 3 functional limitations in mobility, strength, and fine motor skills (n = 13,129), Health and Retirement Study, 2006 and 2008. Bars, 95% confidence interval. (COPD, chronic obstructive pulmonary disease).

Figure 2.

Adjusted odds ratio for reduced lung function (<80% of predicted peak (PEF)) according to chronic diseases and demographic factors among respondents who predicted that they had a <50% probability of living at least 10 more years (n = 1,568), Health and Retirement Study, 2006 and 2008. Bars, 95% confidence interval. (COPD, chronic obstructive pulmonary disease).

Figure 3.

Adjusted odds ratio for reduced lung function (<80% of predicted peak expiratory flow (PEF)) according to chronic diseases and demographic factors among respondents who were hospitalized at any time in the subsequent 2 years (n = 6,398), Health and Retirement Study, 2006. Bars, 95% confidence interval. (COPD, chronic obstructive pulmonary disease).