Sex disparities in self-reported physical functioning: True differences, reporting bias, or incomplete adjustment for confounding?

Objectives: To determine whether sex disparities in self-reported physical functioning remain after adjusting for potential confounding factors and to assess associations for possible reporting bias. Design: Cross-sectional survey. Setting: U.S. population of noninstitutionalized older adults. Participants: Women and men aged 60 and older (N=5,396) who participated in the Third National Health and Nutrition Examination Survey. Measurements: Degree of self-reported limitation in 11 physical functions. Results: In unadjusted models, women reported more limitations than men in 10 of 11 tasks. In multivariate ordinal logistic regression models that included adjustment for age, race or ethnicity, education level, comorbidities, smoking, hemoglobin, serum albumin, knee pain, body mass index, skeletal muscle index, and physical performance tests, women reported more limitations only in lifting or carrying 10 pounds (adjusted odds ratio=2.03, 95% confidence interval=1.45-2.84). There was no evidence of systematic reporting differences between men and women for limitations in lifting or carrying 10 pounds relative to the degree of limitation predicted by the model. Conclusion: Older women have similar degrees of self-reported limitation in physical functioning as older men of the same age, health, and physical abilities.