Background: Cross-sectional analyses of kidney function and physical function have identified profound quality of life impairments in people with advanced kidney dysfunction. No data are currently available, however, on how kidney function decline may be associated with physical function.
Methods: We undertook a study of kidney function decline and physical function in 2544 women participating in the Nurses' Health Study. Glomerular filtration rates (GFR) were estimated using the four-variable MDRD equation from plasma creatinine measured in blood collected in 1989 and 2000. Physical function was assessed by the Physical Function Sub-Scale (PFS) score of the Short Form 36 (SF-36) in a questionnaire administered in the year 2000. PFS scores have been shown to correlate well with direct measures of physical function.
Results: In the year 2000, the median age was 67 years, median body mass index (BMI) was 25.6 kg/m(2), 48.5% had hypertension and 5.8% had diabetes. There were 427 women (16.8%) who experienced an >/=25% decline in eGFR between 1989 and 2000. Median PFS in 2000 for those with an eGFR decline of >/=25% was 80 compared to a PFS score of 85 for those without (P < 0.001). In fully adjusted models, the presence of an eGFR decline of >/=25% was independently associated with a 3.5-point lower PFS score (95% CI -5.4 to -1.5). Also, an eGFR decline of >/=25% was independently associated with an increased odds ratio of being in the lowest quartile of PFS score (OR 1.37; 95% CI 1.04-1.81).
Conclusions: We conclude that an eGFR decline of >/=25% over 11 years is independently associated with lower physical function in women.