Poor self-rated health is significantly associated with elevated C-reactive protein levels in women, but not in men, in the Japanese general population

Objective: Self-rated health (SRH) is associated with risk for mortality, but its biological basis is poorly understood. We examined the association between SRH and low-grade inflammation in a Japanese general population.

Methods: A total of 5142 men and 11,114 women aged 40 to 69years were enrolled. SRH was assessed by a single question and classified into four categories: good, rather good, neither good nor poor, and poor. Serum high-sensitivity C-reactive protein (hsCRP) levels were measured by the latex-enhanced immunonephelometric method. Elevated CRP was defined as hsCRP level of 1.0mg/L or higher. The association between SRH and elevated CRP was evaluated by using logistic regression with adjustment for age, socioeconomic status (job status, education and marital status), health-related behaviors (smoking status, drinking status, exercise habits and sleep duration), and cardiovascular risk factors (body mass index, systolic blood pressure, total- and HDL-cholesterol, HbA1c and prevalent stroke and/or myocardial infarction).

Results: Compared to persons with good SRH, persons with poor SRH had significantly higher risk for elevated CRP: age-adjusted ORs (95% CIs) were 1.33 (1.01-1.76) in men and 1.66 (1.36-2.02) in women. The significant association remained even after adjustment for socioeconomic status, health-related behaviors and cardiovascular risk factors in women, whereas the significance disappeared in men.

Conclusion: Poor SRH is associated with low-grade inflammation in both sexes. In women, but not in men, the association is independent of potential confounders. These findings provide an insight into the biological background of SRH in a general population.