A large-scale rural population study included approximately 27,935 men and women, finding that sleep quality might predict risk of coronary heart disease.
A recent study in rural Chinese areas found that poor sleep quality and a shorter night sleep duration were associated with coronary heart disease (CHD), with a stronger association in women. Investigators concluded the association may act as a marker for early identification of patients at-risk to develop CHD.
The large-scale study included a final sample of 27,935 participants from the Henan Rural Cohort. Of participants, 11,177 (40.01%) were men and 16,758 (59.99%) were women, all of whom had sleep information analyzed via the Pittsburgh Sleep Quality Index (PSQI).
Corresponding author Chongjian Wang, MD, PhD, MPH, department of epidemiology and biostatistics, College of Public Health, Zhengzhou University, Henan, China, and colleagues, identified a total of 1506 patients that had CHD within the sample. The impact of sleep quality on CHD was observed in 3 PSQI score increments (3-5, 6-6, and ≥ 9), with the relationship more prevalent in women at all levels. Men with a PSQI score of 3-5 had an OR of 1.42 (95% CI, 1.16-1.75), those with a score of 6-8 had an OR of 2.08 (95% CI, 1.60-2.69), and those with a score of 9 or more had an OR of 1.56 (95% CI, 1.02-2.39). Comparably, women with a PSQI score of 3-5 had an OR of 1.43 (95% CI, 1.19-1.71), those with a score of 6-8 had an OR of 1.97 (1.62-2.40), and those with a score of 9 or more had an OR of 2.83 (2.28-3.51).
When comparing participants with PSQI scores lower than 3, participants with a score between 3-5, 6-8, and 9 or greater had ORs of 1.42 (95% CI, 1.24-1.63), 1.99 (95% CI, 1.70-2.33), and 2.56 (95% CI, 2.13-3.08), respectively.
“The present study found that shorter sleep duration and poorer sleep quality were both associated with the prevalence of CHD. Interaction of night sleep duration and night sleep quality on CHD was also observed in women but not in men,” Wang et al wrote. “To our knowledge, this study is the first one exploring the independent relationship and interaction of night sleep duration and sleep quality on CHD in rural populations.”
Evaluating nightly sleep duration, men and women who slept less than 5 hours, 5 hours, or 9 or more hours each night were compared to a reference group of those with a nightly sleep duration of 7 hours. Those getting less than 5 hours had an OR of 1.77 (95% CI, 1.28-2.44), those getting 5 hours had an OR of 1.28 (95%, 1.01-1.61) and those getting 9 or more hours had an OR of 1.20 (95% CI, 1.02-1.42), when compared to the reference group.
Investigators found that patients with CHD were more likely to be older, married, smoke, drink alcohol, snore, and have lower education. Additionally, they were more likely to have a somewhat higher body mass index, worse sleep quality, lower sleep duration, and a family history of CHD.
The final sample from the Henan Rural Cohort Study was determined following the investigation of 39,259 patients and the exclusion of those without data on nightly sleep duration (n = 9509), those on night shifts (n =1505), and those with a history of cancer (n = 285). Data collection included a questionnaire interview, a physical exam, as well as laboratory testing.
Investigators noted limitations to the study, including the cross-sectional design, as well as the fact that sleep data was self-reported by patients, introducing potential recall bias. Unknown confounders were also mentioned, as while several were included, there may be additional covariates that would affect the association.