Predictors of Mortality in Elderly Subjects with Obstructive Airway Disease: The PILE Score

Mehrotra, Nitin; Freire, Amado X.; Bauer, Douglas C.; Harris, Tamara B.; Newman, Anne B.; Kritchevsky, Stephen B.; Meibohm, Bernd; Health ABC Study,

doi:10.1016/j.annepidem.2009.11.005

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Volume 20, Issue 3 , Pages 223-232, March 2010

Predictors of Mortality in Elderly Subjects with Obstructive Airway Disease: The PILE Score

Nitin Mehrotra, PhD
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis
Amado X. Freire, MD
- Department of Medicine, University of Tennessee Health Science Center, Memphis
Douglas C. Bauer, MD
- Department of Epidemiology and Biostatistics, University of California, San Francisco
Tamara B. Harris, MD
- Laboratory of Epidemiology, Demography and Biometry, National Institute on Aging, Bethesda, MD
Anne B. Newman, MD
- Department of Epidemiology and Medicine, University of Pittsburgh, Pittsburgh, PA
Stephen B. Kritchevsky, PhD
- Sticht Center on Aging, Wake Forest University, Winston-Salem, NC
Bernd Meibohm, PhD
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis
- Address correspondence to: Bernd Meibohm, PhD, FCP, University of Tennessee Health Science Center, Dept. of Pharmaceutical Sciences, College of Pharmacy, 874 Union Ave., Suite 5p, Memphis, TN 38163.
Health ABC Study

Received 20 May 2009; accepted 25 November 2009.

Purpose

To identify significant covariates in addition to spirometry that predict mortality in elderly subjects with obstructive airway disease (OAD).

Methods

Two hundred sixty-eight (268) participants with OAD from the Health, Aging and Body Composition study, a community-based observational cohort of well-functioning elderly aged 70-79 years, were followed on average for 6.1 years. Covariates related to pulmonary and physical function, comorbidity, demographics, and three inflammatory markers (interleukin-6, tumor necrosis factor-alpha, C-reactive protein) were evaluated for their association with all-cause mortality (31%) by means of Kaplan Meier analysis and Cox proportional hazards modeling.

Results

Percent predicted forced expiratory volume in one second (PPFEV1; hazard ratio [HR] = 2.03, p < 0.0001), knee extensor strength (HR = 1.36, p = 0.0002), interleukin-6 (HR = 1.37, p = 0.0002) and 400 m corridor walk time (HR = 1.24, p = 0.008) significantly predicted mortality. A multidimensional index, the PILE score, was constructed from PPFEV₁, interleukin-6, and knee extensor strength. Each one-point increase in PILE score (range: 1-10) was associated with a 30% increase in mortality (95% confidence interval: 0.16-0.47) after adjusting for age, race, gender, smoking, and comorbidity, resulting in a 10.4-fold higher risk of death between the highest and lowest risk category.