The Impact of Multimorbidity on Resting Metabolic Rate in Community-Dwelling Women over a Ten-Year Period: A Cross-Sectional and Longitudinal Study.

Objectives: Ageing has been associated with increasing multimorbidity. This study investigated whether the number of diseases is a predictor of resting metabolic rate (RMR) and its long-term changes in community-dwelling elderly women.

Subjects And Design: Cross-sectional and longitudinal data, obtained over ten years with repeated follow-ups, from 180 women aged 60 - 86 years and with a BMI of 18 - 43 kg/m2 at baseline were analyzed.

Measurements: RMR was measured using indirect calorimetry and body composition by bioelectrical impedance analysis. Diagnosed diseases were assessed by a questionnaire comprising 23 disease categories. Subjects with 0 - 2 diseases were classified as relatively healthy and with > 2 diseases as multimorbid.

Results: At baseline, relatively healthy (N = 75) and multimorbid (N = 105) women did not differ in RMR. During the ten-year follow-up, the median (range) number of diseases increased from 2 (0 - 2) to 4 (0 - 8) in relatively healthy and from 5 (3 - 11) to 7 (3 - 15) in multimorbid women. In the longitudinal analyses, only women who were multimorbid at baseline showed a significant increase in RMR of 31 kJ/d per additional disease (P = 0.015), adjusted for fat-free mass, fat mass, waist circumference and age.

Conclusion: Increasing multimorbidity in community-dwelling women is associated with an increase in RMR independently of body composition and age.