Systematic Review and Meta-Analysis of Incidence and Prevalence of Endometriosis

Abstract

There is still much controversy regarding the epidemiology of endometriosis. The objective of this work is to conduct a systematic review, and if possible, proceed with a meta-analysis of studies that have analyzed the incidence and prevalence of this condition among women in the general population. The inclusion criteria were papers published after 1997 that had reported data of the incidence or prevalence of endometriosis. The PubMed search engine was used to identify papers meeting the inclusion criteria from 1997 to 2019, with an additional manual search for the identification of potentially eligible studies. The search was limited to papers published in English. The risk of bias was assessed according to the Joanna Briggs Institute Critical Appraisal Checklist. As a result, 27 papers, which included a total of 28,660,652 women, were classified according to the type of design and sources of information in five subgroups. Pooled estimates of prevalence for studies with self-reported data were 0.05 (95% CI: 0.03; 0.06), 0.01 for population-based integrated information systems (95% CI: 0.01; 0.02), and 0.04 (95% CI 0.04; 0.05) in studies using other designs. The pooled incidence rate of endometriosis was: 1.36 per 1000 person-years (PY) (95% CI: 1.09; 1.63) for studies based on hospital discharges, 3.53 per 1000 PY (95% CI: 2.06; 4.99) for cohort studies, and 1.89 per 1000 PY (95% CI: 1.42; 2.37) for population-based integrated information systems. Meta-analysis indicated high heterogeneity based on I-squared statistics. This significant variability may not only be due to methodological issues and the specific limitations of the different designs and data analyzed, including case definitions and subject selection strategies, but also to the inherent heterogeneity of endometriosis. Epidemiological studies with appropriate study designs remain necessary to provide a valid estimation of the population burden of endometriosis.

Keywords: endometriosis; epidemiology; numerical data; statistics.

Figure A1

Funnel plot for prevalence data. Note: blue dots represent individual studies; the outer dotted line indicates the triangular region within which 95% of studies are expected to lie in the absence of both biases and heterogeneity; the solid vertical line represents the line of no effect, derived using fixed-effect meta-analysis.

Figure A2

Funnel plot for incidence data. Note: blue dots represent individual studies; the outer dotted line indicates the triangular region within which 95% of studies are expected to lie in the absence of both biases and heterogeneity; the solid vertical line represents the line of no effect, derived using fixed-effect meta-analysis.

Figure 1

PRISMA flowchart.

Figure 2

Meta-analysis of the prevalence of endometriosis based on self-Reported questionnaires. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).

Figure 3

Meta-analysis of the prevalence of endometriosis based on population-based integrated information systems. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).

Figure 4

Meta-analysis of the prevalence of endometriosis based on studies using data from other sources. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).

Figure 5

Meta-analysis of the incidence of endometriosis per 1000 person-years based on hospital discharge databases. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).

Figure 6

Meta-analysis of the incidence of endometriosis per 1000 person-years based on the data from cohort studies. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).

Figure 7

Meta-analysis of the incidence of endometriosis per 1000 person-years based on population-based integrated information system data. Note: black lines with squared dots—the prevalence with confidence intervals for each individual study; rhombus—pooled prevalence with confidence interval; red dotted line—line of no effect (studies crossing the line are not statistically different).