Table 1 Characteristics of studies included in the present systematic review and meta-analysis. HS hidradenitis suppurativa, n number of cases, ICD-10 10th revision of the International Statistical Classification of Diseases and Related Health Problems, SNOMED CT SNOMED Clinical Terms
From: Hidradenitis suppurativa and acne vulgaris and conglobata—systematic review and meta-analysis
Author | Year | Study period | Country | Design | n (HS) | n (controls) | Data source | Selection of HS cases | Selection of controls | Matching | Mean age (years) | Females (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ingram | 2018 | 2013 | UK | Retrospective case-control | 69,842 (proxy) | 93,869 | Clinical Practice Research Datalink (CPRD) | Proxy cases: Based on clinical features and algorithm, confirmed by validation questionnaire | General population participants in the database without diagnosis of HS | 1: 1 matched based on age, sex and registration at the same primary care practice, obesity, diabetes, smoking, comorbidities | – | – |
24,027 (physician-diagnosed) | 93,869 | Clinical Practice Research Datalink (CPRD) | Physician diagnosed cases: Codes M25y100 (hidradenitis) and M25y111 (hidradenitis suppurativa) | General population participants in the database without diagnosis of HS | 1: 1 matched based on age, sex and registration at the same primary care practice, obesity, diabetes, smoking, comorbidities | – | – | |||||
Kimball | 2018 | 1999–2014 | USA | Retrospective case-control | 2292 (mild HS) | 2292 | OptumHealth Care Solutions, Inc. database | At least two diagnoses for HS (ICD-9 code 705.83) recorded on different dates between January 1999 and March 2014 | Database participants over the same study period without diagnosis for HS | 1:1 matching based on age, sex, region of residence, healthcare plan | 42.19 vs 42.19 | 74 vs 74 |
3065 (severe HS) | 3065 | OptumHealth Care Solutions, Inc. database | HS severity based on predetermined clinical characteristics | Database participants over the same study period without diagnosis for HS | 1:1 matching based on age, sex, region of residence, healthcare plan | 42.19 vs 42.19 | 71 vs 71 | |||||
Lee | 2018 | 2007–2016 | Korea | Retrospective case-control | 28,516 | 142,580 | Korean National Institute of Health database | Diagnosed by ICD-10 code I.729 between January 2007 and December 2016 | Random selection of patients from a database without diagnosis of HS | 1:5 matching based on age and sex. Adjustment for age, sex, socioeconomic status, diabetes, hypertension, hyperlipidaemia | 33.6 vs 33.6 | 38.7 vs 38.7 |
Wertenteil | 2018 | 2012–2017 | USA | Retrospective case-control | 48,050 | 16,899,470 | Explorys developed by International Business Machines (IBM) Corporation | SNOMED-CT term “hidradenitis”, which has one-to-one mapping with the ICD-9 code for hidradenitis (705.83) | Database participants without diagnosis for HS | Adjustment for age, sex, obesity, smoking status, PCOS status | 18-44y: 60 vs 39.6; 45-64y: 30.1 vs 33; ≥65y: 9.8 vs 27.4 | 74.4 vs 56.5 |