Reproducibility of the Endometriosis Fertility Index: a prospective inter-/intra-rater agreement study

Abstract

Objective: To evaluate the reproducibility of the Endometriosis Fertility Index (EFI).

Design: Single-cohort prospective observational study.

Setting: University hospital.

Population: Women undergoing laparoscopic resection of any rASRM-stage endometriosis.

Methods: Details of pre- and peroperative findings were collected into a coded research file. EFI scoring was performed en-bloc by three different raters (expert-1 [C.T.], expert-2 [C.M.], junior [C.B.]). Required sample size: 71. Definitions used for agreement: clinical (scores within same range: 0-4, 5-6, 7-10) and numerical (difference ≤1 EFI point).

Main outcome measures: Primary outcome: rate of clinical agreement between two experts.

Secondary outcomes: expert numerical agreement, clinical and numerical agreement between expert-1 and junior, and within expert-1 (intra-observer), agreement of rASRM score and -stage.

Results: A near 'inter-expert' clinical agreement rate (1.000, 95% CI 0.956-1.000; P = 0.0149) was observed. The numerical agreement between two experts was also high (0.988, 95% CI 0.934-1.000); similarly, high agreement rates were observed for both 'junior-expert' comparisons (clinical 0 .963, 95% CI 0.897-0.992; numerical 0.988, 95% CI 0.934-1.000) and 'intra-expert' comparisons (clinical 0.988, 95% CI 0.934-1.000; numerical 1.000, 95% CI 0.956-1.000). Reasons for disagreements were different scoring of the least-function score and disagreements in rASRM scores. The reproducibility of the rASRM score was clearly inferior to that of the EFI for all comparisons.

Conclusion: The EFI can be reproduced reliably by different raters, further supporting its use in daily clinical practice as the principal clinical tool for postoperative fertility counselling/management of women with endometriosis.

Tweetable abstract: A study confirming the high reproducibility of the EFI substantiates its use in daily clinical practice.

Keywords: Classification; endometriosis; infertility; laparoscopy; reproducibility of results.