Assessment of functional capacity and sleep quality of patients with chronic heart failure.
Taofeek O Awotidebe, Victor O Adeyeye, Rufus A Adedoyin and 6 others
PMID 30931035WHAT IT FOUND
Patients with chronic heart failure had worse sleep quality scores, 8.7 ± 1.6 versus 3.8 ± 1.3, where higher is worse, and walked 242.4 ± 30.1 metres versus 467.1 ± 65.6 metres in controls.
Key findings
01Patients with chronic heart failure had mean PSQI total scores of 8.7 ± 1.6 versus 3.8 ± 1.3 in controls (p = 0.001), with higher scores indicating worse sleep quality.
02Patients with chronic heart failure walked 242.4 ± 30.1 metres versus 467.1 ± 65.6 metres (p = 0.001), and estimated VO2max was 4.62 ± 0.50 versus 11.3 ± 1.6 mL/kg/min (p = 0.001).
03Among patients, PSQI total score was negatively correlated with functional capacity (r = -0.362; p = 0.001), while controls showed a positive correlation (r = 0.481; p = 0.041).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study did not test any treatment, so it cannot show that poor sleep caused lower functional capacity or that any intervention would change either outcome. Sleep quality was measured only by the self-reported PSQI, so recall and estimation bias are possible. Patients were taking several medications, including antihypertensive drugs, which the authors say could affect functional capacity and confound the results. The patient and control groups differed in BMI (30.4 ± 7.0 versus 28.6 ± 6.3; p = 0.042), and blood pressure and BMI were associated with sleep quality in the analysis. Controls were recruited from hospital staff and patients' relatives, so they may not represent the wider healthy population.
Declared interests
The authors declared no competing interests. The paper acknowledges technical support from the Consortium for Advanced Research Training in Africa, funded by the Wellcome Trust, UK Department for International Development, Carnegie Corporation of New York, Ford Foundation, Swedish International Development Corporation Agency, Google.Org, and the MacArthur Foundation.
The easy way to misread this
Do not read the lower walking distance and worse sleep scores as proof that poor sleep caused reduced functional capacity. This was a case-control study that measured both without testing treatment.