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

To investigate the value of hyponatremia as a predictive marker for complicated appendicitis. 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. 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 = 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 = 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. 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.