Table 1.
Baseline characteristic of included observational studies.
| Author | Study design | Year | Location | Definition of HS patients | Definition of outcome event | Female percentage case/control (%) | Mean age (yo) case/control | Adjustment | No. of participants | NOS |
|---|---|---|---|---|---|---|---|---|---|---|
| Ingram et al. (11) | case-control (proxy cases) | 2018 | UK | CPRD Read code algorithms identifying clinical features. Validated by subsequent questionnaire | Read codes in CPRD | NA | NA | age, sex and registration at the same primary care practice | 163711 | 7 |
| Ingram et al. (11) | case-control (physician-diagnosed cases) | 2018 | UK | Read codes in CPRD and ICD-10-based diagnosis | Read codes in CPRD | NA | NA | age, sex and registration at the same primary care practice | 117896 | 7 |
| Lee et al. (12) | cross sectional | 2018 | Korea | at least two documented physician contacts based on ICD-10 diagnosis | at least 2 physician validated ICD-10-based diagnosis | 38.7/38.7 | 33.6/33.6 | age, sex, socioeconomic status and the presence of diabetes, hypertension and dyslipidemia. | 171096 | 6 |
| Kimball et al. (15) | cohort (moderate HS) | 2018 | US | at least two ICD-9-based diagnoses | medical claims recorded | 74/74 | 42.19/42.19 | age, sex, region of residence, and healthcare plan | 4584 | 7 |
| Kimball et al. (15) | cohort (severe HS) |
2018 | US | at least two ICD-9/ICD-10-based diagnosis diagnoses and experienced at least one of the disease severity indicators | medical claims recorded | 71/71 | 42.19/42.19 | age, sex, region of residence, and healthcare plan | 6130 | 7 |
| Andersen et al. (10) | cross sectional | 2020 | Denmark | ICD-10-based diagnosis HS | ICD-10-based diagnosis | 87.5/NA | NA | NA | 440 HS group/NA for control | 5 |
| Schneeweiss et al. (16) | cohort | 2020 | US | at least three ICD-9/ICD-10-based diagnosis or more than one HS diagnosis by a dermatologist | NA | 75.5/76.7 | 36.6/37.6 | age, sex, region, number of outpatient visits, number of unique medications, use of systemic biologic or nonbiologic immunomodulatory agents, comorbidities, combined comorbidity score | 121744 | 6 |
| Schneeweiss et al. (17) | cohort | 2021 | US | at least three ICD-9/ICD-10-based diagnosis on or more than one HS diagnosis by a dermatologist | NA | 75.5/76.6 | 36.48/37.93 | age, sex, health care utilization patterns, comorbidities, comedications, Gagne combined comorbidity score | 132896 | 6 |
| Hua et al. (18) | cross sectional | 2021 | US | at least two ICD-9/ICD-10-based diagnosis | ICD9/10 diagnosis record | 73.6/73.6 | 40.7/40.7 | age, sex, race, index date, obesity, tobacco use | 150337 | 7 |
| Kirsten et al. (19) | cross sectional | 2021 | German | Assessed by dermatologist based on clinical exams and findings | Assessed by dermatologists | 38.6/47.8 | (pooled)43.6 | NA | 20112 | 5 |
| Prens et al. (20) | cross sectional | 2021 | Netherlands | Self-reported by validated questionnaire | Self-reported by validated questionnaire | 73.5/60.1 | 52.1/56.0 | age, sex, BMI, smoking status and socioeconomic status | 56084 | 7 |
| Sokumbi et al. (21) | cross sectional | 2022 | US | ICD-10 diagnosis and validation of dermatologists | ICD-10 diagnosis | 73.0/73.0 | 35.4/35.5 | Age, sex, index date | 2320 | 6 |
HS, Hidradenitis suppurativa; ICD-9, International Classification of Diseases, 9th Revision; ICD-10, International Classification of Diseases, 10th Revision;
y/o, years old; NA, not available; NOS, Newcastle-Ottawa Scale.