Table 1.
Main characteristics of the cohort studies included in the meta-analysis of incident CAD in hidradenitis suppurativa
| Egeberg et al.[19] | Andersen et al.[22] | Hung et al.[20] | Reddy et al.[21] | |
|---|---|---|---|---|
| Country | Denmark | Denmark | Taiwan | United States |
| Study design | Retrospective cohort | Retrospective cohort | Retrospective cohort | Retrospective cohort |
| Year of publication | 2016 | 2020 | 2019 | 2020 |
| Total number of participants | Cases with HS: 5,964 Comparators without HS: 29,404 | Cases with HS: 14,488 Comparators without HS: N/A | Cases with HS: 478 Comparators without HS: 1,912 | Cases with HS: 49,862 Comparators without HS: 1,421,223 |
| Recruitment of participants | Patients with HS were identified from the Danish National Patient Registry database from January 1st, 1997 to December 31st, 2011. This database covers all citizens of Denmark. Comparators without HS were randomly selected from the same database at 1:5 ratio. They were sex, age and calendar time matched to cases. Participants with diagnosis of MI or stroke prior to the study were excluded. | Patients with HS and comparators were identified from the Danish National Patient Registry from January 1st, 1994 to April 10th, 2018 The rest of the residents of Denmark without HS served as comparators. | Patients with HS and comparators were identified from the longitudinal health insurance database of Taiwan from 2000 to 2013. The longitudinal health insurance database is a subset of the Taiwan National Health Insurance Research database which covers inpatient and outpatient care of almost all residents of Taiwan. Comparators without HS were randomly selected from the same database at 1:4 ratio. They were sex, age and calendar time matched to cases. Participants with diagnosis of MI or stroke before 2000 were excluded. | Patients with HS were identified from the Explorys database which encompassed 27 integrated healthcare organization of over 56 million unique patients from January 1, 1999, and April 1, 2019. Comparators without HS were all other patients in the database who did not have diagnosis codes for HS. |
| Diagnosis of HS | Presence of ICD-8-CM (705.91) or ICD-10-CM (L73.2) for HS in the database | Presence of ICD-10-CM (L73.2) diagnosis code for HS in the database or the presence of ICD-10-CM surgical procedural codes for procedures likely for HS at least twice within a 6-month period | Presence of ICD-9-CM (705.83) made by dermatologist at least four times | Presence of at least 1 ICD-9-CM (705.83) or ICD-10-CM (L73.2) for HS in the database |
| Diagnosis of CAD | Presence of ICD-10-CM (I21-I22) for MI in the database | Presence of ICD-10 codes (I21, I210, I210A, I210B, I211, I211A, I211B, I212, I213, I214, I219) for acute MI in the database | Presence of ICD-9-CM (411-414) for CAD in the database | Presence of ICD-9 code (410.x) or ICD-10 code (I21. x-I22.x) for MI in the database |
| Follow-up | Until migration, death or occurrence of the end point of interest | Until migration, death or occurrence of the end point of interest | Until migration, occurrence of the end point of interest or the end of 2013 | Until the date of last database encounter or occurrence of the end point of interest |
| Average duration of follow-up (years) | Mean: 7.1 | Median: 8.8 | Mean for cases with HS: 10.7 Mean for comparators without HS: 11.8 | Mean for cases with HS: 4.2 Mean for comparators without HS: 8.2 |
| Average age of participants (years) | Cases with HS: 37.7 Comparators without HS: 37.6 | Cases with HS: 37.6 Comparator without HS: N/A | Cases with HS: 39.8 Comparators without HS: 40.0 | Cases with HS: 38.3 Comparators without HS: 44.7 |
| Percentage of female | Cases with HS: 72.9 Comparators without HS: 73.1 | Cases with HS: 68.3 Comparator without HS: N/A | Cases with HS: 51.7% Comparators without HS: 51.7% | Cases with HS: 76.2% Comparators without HS: 58% |
| Comorbidities | Cases with HS: Alcohol abuse: 3.3% Arrhythmia: 0.6% DM: 4.3% Depression: 1.2% HTN: 5.6% IBD: 0.8% VTE: 0.8% Comparators without HS: Alcohol abuse: 1.3% Arrhythmia: 0.4% DM: 1.4% Depression: 0.4% HTN: 2.8% IBD: 0.3% VTE: 0.3% | N/A | N/A | Cases with HS: Smoking status: 48.2% HTN: 27.1% Hyperlipidemia: 20.8% DM: 12.5% CCI score 0.6 Comparators without HS: Smoking status: 26.2% HTN: 7.4% Hyperlipidemia: 5% DM: 2.7% CCI score 0.1 |
| Variables adjusted in multivariate analysis | Age, sex, smoking, comorbidities, medication and socioeconomic status | N/A | Age, sex, CCI, alcoholism, obesity and residence/regions | Age, sex, race, HTN hyperlipidemia, DM, smoking status, BMI, CCI score and baseline medication use |
| Newcastle-Ottawa score | Selection: 4 Comparability: 2 Outcome: 3 | Selection: 3 Comparability: 0 Outcome: 3 | Selection: 4 Comparability: 2 Outcome: 3 | Selection: 4 Comparability: 1 Outcome: 3 |
CAD=Coronary artery disease, CCI=Charlson comorbidity index, DM=Diabetes mellitus, HS=Hidradenitis suppurativa, HTN=Hypertension, IBD=Inflammatory bowel disease, ICD=International classification of diseases, MI=Myocardial infarction, N/A=not available, VTE=Venous thromboembolism