Differential misclassification of cognitive impairment by sex among hip fracture patients

Males have worse outcomes after hip fracture than female counterparts. Cognitive impairment (CI) also increases the risk of poor recovery from hip fracture; however, CI is under-recognized. Patient sex may contribute to this under-recognition through differential misclassification. The objective of this study was to measure under-recognition and differential misclassification of CI by patient sex.

A cross-sectional analysis of baseline data from an observational cohort study of community-dwelling hip fracture patients aged 65 and older (n = 339; females = 171, males = 168) recruited from eight hospitals in the greater Baltimore, MD area within 15 days of hospitalization for surgical repair with cognitive testing within 22 days of admission. Indication of Alzheimer's disease or related dementias and/or delirium as a postoperative complication in the medical record was considered evidence of documented CI. Observed CI was measured with the Modified Mini-Mental State Examination (3MS, ≤78). Source of cognitive impairment identification (SCI) was defined as: "3MS Only," "Hospital Record Only," "Both," "No CI" was compared between males and females using logistic regression.

Males had more comorbidities and worse physical status upon admission, but otherwise had similar hospital experiences. SCI distribution was 12.7% "3MS Only" (n = 42), 11.5% "Hospital Record Only" (n = 38), 9.4% "Both" (n = 31), and "No CI" (n = 219). Males were more likely to be identified with CI using the "3MS Only" and "Both," and females were more likely to have no indication of CI.

There were sex differences in the documentation of CI versus observed impairment. Males had more CI using direct testing. This may be contributing to sex differences in recovery outcomes after hip fracture. Results support the implementation of cognitive testing in hip fracture patients to reduce the impact of differential misclassification by patient sex.