Inter-examiner Reproducibility of Clinical Examination Tests for Athletes with Longstanding Groin Pain

The "Doha agreement meeting on terminology and definitions" aimed to simplify the heterogeneous taxonomy of groin injuries by creating a straightforward classification system based on patient history and clinical examination. Following this classification system, groin pain can be divided into four defined clinical entities (adductor-, inguinal-, iliopsoas- and/or pubic-related groin pain), hip related groin pain, and/or other causes for groin pain.

In the Doha classification, pain on palpation, resistance and/or stretching are the key clinical findings for categorizing in the four clinical entities. However, this classification does not describe how these clinical tests should be performed and if these tests are reproducible.

The primary aim of this study is to evaluate the inter-examiner reproducibility of clinical palpation, resistance and stretch tests for longstanding groin pain in athletes. The secondary aim is to identify the proportion of positive clinical tests for each clinical entity diagnosis.

Two blinded examiners (a physiotherapist and a general surgeon, both specialized in groin injuries with >10 years experience) will assess each athlete with longstanding groin pain following a standardized examination protocol. Prior to clinical examination, participants will be requested to complete a standardized form for patient/injury characteristics and injury history, the Copenhagen Hip and Groin Outcome Score (HAGOS) and the Oslo Sports Trauma Research Center (OSTRC) overuse injury questionnaire. The HAGOS is a patient-reported outcome measure, which quantifies a patient's current subjective perception of their hip and groin pain within the last week on six subscales, each with a score between 0 and 100.The OSTRC overuse injury questionnaire has a focus on groin problems within the last week.

The standardized clinical examination protocol consists of palpation, resistance and stretch-tests and are used to categorize athletes into defined clinical entities. A score on the Numeric Pain Rating Scale (0-10) will be asked to the patient for each test, where pain during the test has to correspond to the injury pain. Each score from 1-10 will be considered as positive for analysis. If the pain is just from palpation and not related to the injury, the test will be considered negative.

Inter-examiner reliability will be analysed using Cohen's Kappa statistic (κ), including 95% confidence intervals for dichotomous variables. Linear weighted κ will be calculated for ordinal variables. Additionally, the absolute positive agreement and negative agreement between the two examiners and bias index will be calculated. The mean prevalence of each positive clinical tests of both clinicians will be reported for each entity diagnosis. Furthermore, agreement analysis for the palpation tests of the four defined clinical entities of groin pain will also be grouped: adductor-, iliopsoas-, inguinal- (with and without invagination) and pubic palpation.

For the 3 main defined clinical entities (adductor-, inguinal- and iliopsoas-related groin pain), a prevalence is expected between 30-60% in our research population. Assuming that approximately 4 out of every 5 tests (80%) targeting each entity will be positive, we expect a prevalence of positive tests of approximately 24-48% in the whole sample. With an expected Kappa of at least 0.8, with a 95% confidence interval lower limit of 0.4, using a 2-tailed test and assuming no bias between examiners, at least 60 affected sides will be needed for this study. A lower prevalence of positive tests for pubic-related groin pain and subsequent less robust results for clinical tests of this entity will be accepted. No dropout is expected due to the cross-sectional character of the study. We will continue inclusion until we have 60 full data sets.