Spontaneous Resolution of Uncomplicated Appendicitis may Explain Increase in Proportion of Complicated Appendicitis During Covid-19 Pandemic: a Systematic Review and Meta-analysis

BACKGROUND: Reports of an increased proportion of complicated appendicitis during the Covid-19 pandemic suggest a worse outcome due to delay secondary to the restrained access to health care, but may be explained by a concomitant decrease in uncomplicated appendicitis. We analyze the impact of the pandemic on the incidences of complicated and uncomplicated appendicitis. METHOD: We did a systematic literature search in the PubMed, Embase and Web Of Science databases on December 21, 2022 with the search terms (appendicitis OR appendectomy) AND (“COVID” OR SARS-Cov2 OR “coronavirus”). Studies reporting the number of complicated and uncomplicated appendicitis during identical calendar periods in 2020 and the pre-pandemic year(s) were included. Reports with indications suggesting a change in how the patients were diagnosed and managed between the two periods were excluded. No protocol was prepared in advance. We did random effects meta-analysis of the change in proportion of complicated appendicitis, expressed as the risk ratio (RR), and of the change in number of patients with complicated and uncomplicated appendicitis during the pandemic compared with pre-pandemic periods, expressed as the incidence ratio (IR). We did separate analyses for studies based on single- and multi-center and regional data, age-categories and prehospital delay. RESULTS: The meta-analysis of 100,059 patients in 63 reports from 25 countries shows an increase in the proportion of complicated appendicitis during the pandemic period (RR 1.39, 95% confidence interval (95% CI 1.25, 1.53). This was mainly explained by a decreased incidence of uncomplicated appendicitis (incidence ratio (IR) 0.66, 95% CI 0.59, 0.73). No increase in complicated appendicitis was seen in multi-center and regional reports combined (IR 0.98, 95% CI 0.90, 1.07). CONCLUSION: The increased proportion of complicated appendicitis during Covid-19 is explained by a decrease in the incidence of uncomplicated appendicitis, whereas the incidence of complicated appendicitis remained stable. This result is more evident in the multi-center and regional based reports. This suggests an increase in spontaneously resolving appendicitis due to the restrained access to health care. This has important principal implications for the management of patients with suspected appendicitis. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00268-023-07027-z.