This systematic review complies with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement.
2.1 Data sources and search strategies
All studies evaluating men with erectile dysfunction suffering from hyperthyroidism were obtained by searching Pubmed, Embase, Cochrane, and Web of Science databases. The search was conducted from the date of database creation to December 10, 2022. Briefly, the search keywords were (Hyperthyroid OR Primar Hyperthyroidism) AND (Dysfunction, Erectile OR Male Impotence), and only literature with English as the language of publication was collected for all results.
2.2 Study selection
2.2.1 Inclusion criteria:
(1) study subjects aged ≥18;
(2) use of a validated tool for diagnosing ED: e.g., the International Index of Erectile Function (IIEF-5) ;
(3) patients with concomitant hyperthyroidism, given a Relative risk or odds ratio for the diagnosis of erectile dysfunction (ED) in the study.
2.2.2 Exclusion criteria:
(1) Study subjects aged<18;
(2) Duplicate published literature, review literature, animal experimental literature, etc.;
(3) literature for which the required data were not available and the authors could not be contacted;
(4) literature for which the required study data were not available, such as: Relative risk (RR) or odds ratio (odds ratio).
2.3 Data extraction and Quality assessment
Two reviewers (B.L.,Y.L.W.) working independently screened titles and abstracts. Full-text articles obtained from initial screening were retrieved for second-stage screening (fig1). The search strategy was jointly designed by an experienced librarian and two of the investigators. The investigators extracted and recorded all study data in a standardized manner, and consensus was reached through negotiation when there were differences of opinion. The key indicators for data extraction included: author, time of publication, country, method of ED measurement, and number of people in the diseased and normal control groups. Researchers performed quality evaluation of the final included literature based on the Newcastle-Ottawa Scale (NOS).
2.4 Data synthesis
Meta-analysis was performed using Review Manager 5.3 and Stata 16 software, and by software heterogeneity test, when P>0.1 and I2<50%, it suggested good homogeneity of results among studies, and the fixed-effect model was used to combine OR values; conversely, if P≤0.1 and/or I2≥50%, it suggested heterogeneity of results among studies, and further analysis of the reasons for the existence of heterogeneity was needed, and after excluding the obvious. After excluding the effects of obvious clinical heterogeneity and methodological heterogeneity, if the heterogeneity was still relatively large, a random-effects model or a descriptive analysis was used. Publication bias was assessed using funnel plots, Begg's test, and Egger's test.