Prevalence of the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) in Patients With Brucellosis: A Meta-Analysis

Background: Hyponatremia is prevalent amongst hospitalized patients and is associated with adverse outcomes. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common cause of hyponatremia. In our experience in a middle eastern country, we observed a relationship between brucellosis and SIADH associated hyponatremia. Nonetheless, there is limited literature describing this association. Thus, we aimed to systematically review the literature and pool the prevalence of SIADH in patients with brucellosis. Methods: We comprehensively searched PubMed, EMBASE, and Google scholar (first 100 hits) for observational studies ascertaining the prevalence of SIADH in brucellosis patients. We had no age, language, or date limitations. We used a proportion meta-analysis utilizing the random-effects model with double arcsine transformation. I2 was used to ascertain heterogeneity. We used MetaXl software for statistical analysis. The protocol was preregistered at PROSPERO. Results: Our search in PubMed and EMBASE retrieved 107 articles, of which only four observational studies were relevant. Aysha et al. conducted the first analysis of 58 brucellosis patients in which 24% had sodium levels of less than 130 mmol/L. We excluded this study from our quantitative synthesis as the SIADH prevalence could not be accurately ascertained. Finally, the quantitative synthesis comprised three studies encompassing 306 patients and revealed a pooled SIADH prevalence of 20% (95% CI 0-52%, I2 96%). The quality assessment revealed low to moderate quality of included studies. Conclusion: The reported prevalence of SIADH in individual studies included in our analysis ranged from 3-56%. The results were heterogeneous, as depicted by a high I2. This varying prevalence is perhaps due to the varying age of included participants, definitions used by the primary studies, and the included data’s observational nature. Nonetheless, our meta-analysis revealed a relatively high prevalence of SIADH of 20% in patients with brucellosis. Hence, hyponatremia in patients with chronic fever should prompt a workup for SIADH and brucellosis, especially in endemic areas for brucellosis. Larger prospective studies are needed to ascertain the exact prevalence of SIADH in this patient cohort and its impact on the overall prognosis.