Association of serum folate concentrations with cancer mortality among patients with arthritis: a prospective cohort study.

BACKGROUND

Patients with arthritis exhibit abnormal serum folate concentrations and have a higher incidence of cancer. The aim of this study was to investigate the association of serum folate concentrations with cancer mortality among individuals with arthritis.

METHODS

This cohort study included 7,514 patients with arthritis from National Health and Nutrition Examination Survey (NHANES) 1999 to 2016 and NHANES III (1988-1994). Death outcomes were ascertained by linkage to National Death Index records through 31 December 2019. Serum folate concentrations were categorized into 4 groups, group 1 (≤ 17 nmol/L); group 2 (17-≤34 nmol/L); group 3 (34-≤51 nmol/L); and group 4 (> 51 nmol/L). Cox regression models were used to calculate hazard ratios and 95% confidence intervals for the associations between folate concentrations and the risk of mortality.

RESULTS

During a median follow-up of 9.75 [interquartile range, IQR, 5.75-14.5] years, there were 2,602 all-cause deaths, 949 deaths due to cardiovascular disease, and 478 deaths due to cancer. A non-linear association was observed for folate concentrations with the risk of cancer mortality (P < 0.001) among arthritis patients. Compared with the reference group 2, the hazard ratios for cancer mortality were 1.75 (95% CI, 1.15-2.69) in group 1, 1.70 (95% CI, 1.17-2.46) in group 3, and 1.60 (95% CI, 1.13-2.25) in group 4.

CONCLUSIONS

This study shows that both low and high levels of serum folate are associated with an increased risk of cancer mortality among individuals with arthritis, indicating a potential beneficial role of maintaining moderate serum folate concentrations in decreasing the risk of cancer mortality among this population.