Interaction of nutritional and inflammatory levels on all-cause mortality among individuals with rheumatoid arthritis: a prospective cohort study.

BACKGROUND

Malnutrition and systemic inflammation are frequently prevalent in individuals with rheumatoid arthritis (RA). However, limited studies have explored the combined impacts of nutritional and inflammatory levels on all-cause mortality among RA. This study is aimed at investigating these potential associations.

METHODS

We involved 2213 RA patients from the National Health and Nutrition Examination Survey (2001-2018). Nutritional risk index (NRI) and systemic inflammatory response index (SIRI) were used to evaluate the nutritional and inflammatory status of participants, respectively. Weight-based Kaplan-Meier survival curves and COX proportional hazard models were employed to ascertain the independent and joint association.

RESULTS

Over a median follow-up of 7.98 years, 544 deaths occurred. Following the adjustment for confounding factors, we found that individuals with moderate/severe malnutrition (HR, 2.13; 95%CI, 1.50-3.03) or high SIRI (HR, 1.49; 95%CI, 1.07-2.07) were independently associated with an increased risk of all-cause mortality. Furthermore, the simultaneous moderate/severe malnutrition and high SIRI further elevated the mortality risk (HR, 2.34; 95%CI, 1.53-3.56). An additive interaction was observed between malnutrition and high SIRI, yielding an excess risk of 0.34 (95%CI 0.06-0.62, P = 0.014), and the attributable proportion for the interaction was 20.9% (95%CI 7.6-34.2%).

CONCLUSIONS

This research indicated that malnutrition and high systemic inflammation levels were independent risk factors for the prognosis of RA patients, and co-occurrence can further deteriorate the prognosis. Our findings highlight the importance of maintaining nutrition and anti-inflammation in patients with RA, providing new insights into the prognosis of RA patients.