Association of the prognostic nutritional index (PNI) with the prevalence and mortality of osteoarthritis: a cross-sectional study from NHANES (1999–2018)

Osteoarthritis (OA) is a progressive disease characterized by degenerative changes in articular cartilage. OA has the highest incidence among all categories of arthritis. Currently, the relationship between the prognostic nutritional index (PNI) and the prevalence or mortality from OA remains unclear. The current research aimed to investigate such an association. This research leveraged data sourced from the National Health and Nutrition Examination Survey spanning 1999 to 2018. Weighted logistic regression was employed to examine the association between the PNI and the odds of OA. Weighted Cox regression was adopted to explore the relationship between the PNI and mortality among individuals with OA. Restricted cubic spline (RCS) curves were generated to explore dose-response associations of the PNI with both the prevalence and mortality of OA. Subgroup analyses were implemented to assess the robustness and heterogeneity of the associations across different populations. Finally, sensitivity analyses were implemented to verify the reliability of our findings. The current research encompassed 44,371 participants, among whom 3,934 individuals (8.87%) had OA, and 924 (23.49%) of these OA patients died. Weighted logistic regression revealed a significant inverse association between the PNI and the odds of OA, while weighted Cox regression demonstrated a significant inverse association between the PNI and mortality among individuals with OA. Each one-unit elevation in the PNI was related to an approximately 2.2% reduced odds of OA (odds ratio = 0.978, 95% confidence interval [CI]: 0.969–0.988) and a 7.0% decreased risk of mortality (hazard ratio = 0.930, 95% CI: 0.911–0.949). RCS curves indicated a linear relationship between the PNI and the prevalence of OA ( P = 0.232 for non-linearity) and a significant non-linear relationship between the PNI and the risk of mortality ( P < 0.001 for non-linearity). Subgroup analyses demonstrated an inverse association of higher PNI across various groups against both the prevalence and mortality of OA ( P < 0.05). Notably, the association between PNI and the prevalence of OA was significantly modified by both body mass index (BMI) and hypertension status ( P < 0.05 for interaction). Our research found that an elevated PNI was significantly linked to lower prevalence and mortality of OA. BMI and hypertension appeared to influence the association between the PNI and the odds of OA. This investigation suggests that improving immunonutritional status may be associated with a lower likelihood of OA and a lower mortality among individuals with OA. It offers evidence for personalized preventive measures in clinical practice.