Lying obliquely—a clinical sign of cognitive impairment: cross sectional observational study

Objective To determine if failure to spontaneously orient the body along the longitudinal axis of a hospital bed when asked to lie down is associated with cognitive impairment in older patients. Design Cross sectional observational study. Setting Neurology department of a university hospital in Germany. Participants Convenience sample of 110 older (≥60 years) inpatients with neurological conditions and 23 staff neurologists. Main outcome measures The main outcome measure was the association between the angle of the body axis and the results of three cognitive screening tests (mini-mental state examination, DemTect, and clock drawing test). Staff doctors were shown photographs of a model taken at a natural viewing able to determine their subjective perspective of what constitutes oblique. Results 110 neurological inpatients (mean age 70.9 (SD 6.8) years) were included after exclusions. Evidence of cognitive impairment was found in 34, with scores indicating dementia in eight, according to the mini-mental state examination, and in 11 according to the DemTect. Across all patients, the mean angular deviation of the body axis from the longitudinal axis of the bed (range 0-23°) correlated linearly with the mini-mental state examination (r=−0.480), DemTect (r=−0.527), and the clock drawing test (r=−0.552) scores (P<0.001 for all), even after removing age as a covariate. Overall, 90% of staff neurologists considered a minimal body angle of 7° to be oblique. Angular deviation of at least 7° predicted cognitive impairment according to the three different tests, with specificities between 89% and 96% and sensitivities between 27% and 50%. Conclusion Clinicians might suspect cognitive impairment in mobile older inpatients with neurological disorders who spontaneously position themselves obliquely when asked to lie on a bed.