Xuelian Hong,1 Fengfeng Jiang2 

1Department of Rheumatology and Immunology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua City, Zhejiang Province, 321000, People’s Republic of China; 2Department of Neurosurgery, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua City, Zhejiang Province, 321000, People’s Republic of China

Correspondence: Fengfeng Jiang, Department of Neurosurgery, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, 365 Renmin East Road, Chengzhong Street, Wucheng District, Jinhua City, Zhejiang Province, 321000, People’s Republic of China, Tel +8615258955165, Email fengfengjiang43@163.com

Objective: This study aimed to explore the association between dietary niacin intake and rheumatoid arthritis (RA) in American women through the National Health and Nutrition Examination Survey (NHANES) database.
Methods: A retrospective analysis was conducted based on NHANES 2003– 2016 data. Dietary niacin intake was stratified using weighted quartiles and association of dietary niacin intake with RA was explored using weighted logistic regression models and restricted cubic splines (RCS). Subgroup analysis was conducted, adjusting for all confounding factors, and a likelihood ratio test was utilized to determine significant covariates for the interaction term. Stratified analysis was conducted on significant covariates to determine their impact on the association of dietary niacin intake with RA.
Results: Fourteen thousand five hundred and thirty-nine American women were selected according to inclusion and exclusion criteria, among whom 845 (4.4%) had RA. Compared with American women without RA, American women with RA had significantly lower dietary niacin intake (18.90 vs 21.22, P< 0.001). Logistic regression models and RCS analysis reported a significant linear negative correlation between dietary niacin intake and prevalence of RA (Odds Ratio (OR) < 1, P < 0.05, P-non-linear > 0.05). The interaction-term P-values showed that this association was significantly influenced by poverty income ratio (PIR), education level, Body Mass Index (BMI), and smoking (P for interaction < 0.05). Stratified analysis unveiled that this association was particularly significant in individuals aged ≥ 40 years (OR: 0.98, 95% Confidence Interval (CI): 0.97– 0.99, P < 0.05), PIR > 3.5 (OR: 0.96, 95% CI: 0.93– 0.99, P < 0.05), with a college education or higher (OR: 0.97, 95% CI: 0.94– 0.99, P < 0.01), BMI ≥ 30kg/m² (OR: 0.98, 95% CI: 0.96– 0.99, P < 0.05), non-smokers (OR: 0.97, 95% CI: 0.95– 0.99, P < 0.01), or former smokers (OR: 0.95, 95% CI: 0.95– 0.99, P < 0.05).
Conclusion: Increased dietary niacin intake was associated with a reduced prevalence of RA, especially in women aged ≥ 40, PIR > 3.5, with at least a college education, BMI ≥ 30kg/m², and currently non-smokers.

Keywords: rheumatoid arthritis, dietary niacin intake, women, NHANES