Hyponatremia as a predictor of complicated appendicitis: a systematic review and meta-analysis.

Aim: To investigate the value of hyponatremia as a predictive marker for complicated appendicitis. Methods: PubMed, Embase, Web of Science and Scopus databases were searched for studies published up to 5 June 2024. Studies reporting serum sodium levels in patients with complicated and non-complicated appendicitis and studies reporting the association between baseline hyponatremia and complicated appendicitis were included. A random-effects meta-analysis was performed. Results: Twenty-two studies met the eligibility criteria. Serum sodium levels were measured at arrival or preoperatively in all included studies. Meta-analysis of data from 17 studies showed that preoperative sodium levels were significantly lower in patients with complicated appendicitis vs uncomplicated appendicitis [Mean Difference (MD): -2.58 95% confidence intervals (CI): -3.51, -1.66 I ²  = 98%]. A pooled analysis of 18 studies demonstrated a statistically significant association between preoperative hyponatremia and complicated appendicitis [Odds Ratio (OR): 4.11 95% CI: 3.07, 5.51 I ²  = 93%]. Results remained significant on subgroup analysis for adult and pediatric populations. However, the MD was higher and the OR was higher in the subgroup of pediatric patients. Conclusion: Hyponatremia was identified as a potential predictor for complicated appendicitis. The association between hyponatremia and complicated appendicitis seems to be stronger in pediatric patients as compared with adults.