Kim DY, Nassiri N, de Virgilio C, Ferebee MP, Kaji AH, Hamilton CE, Saltzman DJ. Association Between Hyponatremia and Complicated Appendicitis. JAMA Surg. 2015;150(9):911-912. doi:10.1001/jamasurg.2015.1258
Complicated appendicitis is associated with worse outcomes among patients with acute appendicitis.1 Preoperative identification of patients with a perforated or gangrenous appendicitis may have important clinical implications regarding the timing of surgery and the suitability for nonoperative management strategies. The objective of this study was to identify clinical variables associated with the presence of complicated appendicitis.
Following institutional review board approval from the Los Angeles Biomedical Research Institute in Torrance, California, we conducted a retrospective analysis of adult patients (>18 years of age) who underwent an appendectomy for acute appendicitis at Harbor-UCLA and Olive View–UCLA Medical Centers over a 3.5-year period. Exclusion criteria included pregnancy and a pathologic diagnosis of chronic appendicitis or appendiceal neoplasm. Complicated appendicitis was defined as the intraoperative finding of a perforated or gangrenous appendix. Variables analyzed included findings from history taking and a physical examination, admission laboratory values, and operative details. Statistically significant variables were entered into a multiple logistic regression model to identify independent predictors of complicated appendicitis. The study participants did not provide informed consent because all study data were deidentified.
Of 1550 patients who underwent an appendectomy for acute appendicitis, 409 (26.4%) had complicated appendicitis. These patients were older (P < .001), were more likely to be men (P < .001), and had a higher number of comorbidities (Table 1). The duration of abdominal pain was longer among patients with complicated appendicitis than among those without (48 vs 24 hours; P < .001), and these patients presented more commonly with abdominal guarding (P < .001) and peritonitis (P = .01). The time from admission to operation did not differ between the patients with complicated appendicitis and those without.
Serum sodium levels were lower in patients with complicated appendicitis, whereas lactate levels did not differ between the 2 groups of patients (Table 1). Of the 409 patients with complicated appendicitis, 173 (42.3%) were identified as having a serum sodium level of less than 135 mEq/L (to convert to millimoles per liter, multiply by 1.0). Longer hospital lengths of stay, deep surgical site infections, and return visits to the emergency department were more prevalent among patients with complicated appendicitis.
Exploratory logistic regression analysis identified significant cut points and 4 independent predictors for complicated appendicitis, of which hyponatremia was found to have the strongest association with this outcome (Table 2). The C statistic or area under the curve of the model was 0.71. The Hosmer-Lemeshow goodness-of-fit statistic was P = .90.
Complicated appendicitis is associated with poor outcomes, and its early identification may have implications for patient management, specifically with regard to the timing of operative intervention and the appropriateness of nonoperative management strategies. The finding of hyponatremia at admission may help distinguish necrotizing soft-tissue infections from nonnecrotizing soft-tissue infections2 and is a known risk factor for mortality among patients presenting with necrotizing soft-tissue infections.3 Hyponatremia at admission is also predictive of gangrenous cholecystitis and, more recently, has been associated with perforated colonic pathology among elderly patients who underwent emergency general surgery.4,5
The etiology for hyponatremia in patients with advanced surgical infectious pathology, including complicated appendicitis, is unknown but is likely an antidiuretic hormone–mediated phenomenon. Whether the increase in antidiuretic hormones is appropriate or inappropriate, however, remains to be elucidated. Future investigations accounting for the clinical volume status and key determinants of serum sodium concentration are potentially warranted.
Our study is limited by its retrospective design and lack of data regarding the etiology of hyponatremia in patients with complicated appendicitis. Also, we did not examine all the variables potentially associated with complicated appendicitis; however, the main objective of our study was to analyze readily available and routinely ordered data used in the workup of adult patients with suspected acute appendicitis.
In the appropriate clinical context, hyponatremia in patients with acute appendicitis may be suggestive of complicated appendicitis. Prospective studies are required to confirm this finding and to determine the potential effect of an earlier operative intervention on outcomes.
Corresponding Author: Dennis Y. Kim, MD, Division of Trauma/Acute Care Surgery/Surgical Critical Care, Department of Surgery, Harbor-UCLA Medical Center, 1000 W Carson St, Torrance, CA (firstname.lastname@example.org).
Published Online: July 29, 2015. doi:10.1001/jamasurg.2015.1258.
Author Contributions: Dr Kim had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Kim, de Virgilio.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Kim, Nassiri, Ferebee, Kaji.
Critical revision of the manuscript for important intellectual content: Kim, de Virgilio, Hamilton, Saltzman.
Statistical analysis: Nassiri, Ferebee, Kaji, Hamilton.
Administrative, technical, or material support: Nassiri, de Virgilio.
Study supervision: Kim, de Virgilio, Saltzman.
Conflict of Interest Disclosures: None reported.
Previous Presentation: This paper was presented at the 86th Annual Meeting of the Pacific Coast Surgical Association; February 19, 2015; Monterey, California.