Background: Despite the potentially accompanying negative clinical, epidemiologic, and health economic effects, a large proportion of persons living with the human immunodeficiency virus (HIV) are diagnosed late. Internationally, numerous diseases are known to be HIV indicator diseases. Adequate HIV testing in the presence of HIV indicator diseases could help to diagnose unknown HIV infections earlier. The objective of the HeLP study is to validate published HIV indicator diseases for the German setting and to identify guidelines in terms of these indicator diseases in order to reduce knowledge gaps and increase HIV testing when HIV indicator diseases are diagnosed.

Methods: A mixed methods approach is used. In a first step, published HIV indicator diseases will be identified in a systematic literature review and subsequently discussed with clinical experts regarding their relevance for the German setting. For the validation of selected indicator diseases different data sets (two cohort studies, namely HIV-1 seroconverter study & ClinSurv-HIV, and statutory health insurance routine data) will be analyzed. Sensitivity analyses using different time periods will be performed. Guidelines of HIV indicator diseases validated in the HeLP study will be reviewed for mentioning HIV and for HIV testing recommendations. In addition, semi-standardized interviews (followed by a free discussion) with guideline creators will identify reasons why HIV testing recommendations were (not) included. Subsequently, a random sample of physicians in medical practices will be surveyed to identify how familiar physicians are with HIV testing recommendations in guidelines and, if so, which barriers are seen to perform the recommended tests in everyday care.

Discussion: The HeLP-study adopts the challenge to validate published HIV indicator diseases for the German setting and has the potential to close a knowledge gap regarding this objective. This has the potential to improve targeted HIV testing for patients with HIV indicator diseases and consequently lead to earlier HIV diagnosis.