Table 1. Descriptive Data of the Groups From the Danish National Patient Registrya.
| Characteristic | ICD-10 group (n = 11 929) | Proxy group (n = 2791) | Combined (n = 14 488)b |
|---|---|---|---|
| Alive by first quarter of 2018, No. (% of total Danish population)c | 10 975 (0.19) | 2655 (0.05) | 13 410 (0.23) |
| Age at diagnosis, mean (SD), y | 37.72 (13.01) | 37.38 (15.83) | 37.68 (13.61) |
| Sex, No. (%) | |||
| Male | 3537 (29.7) | 1105 (39.6) | 4587 (31.7) |
| Female | 8392 (70.3) | 1686 (60.4) | 9901 (68.3) |
| Type of HS, No. (%)d | |||
| Familial | 455 (3.8) | 39 (1.4) | 541 (3.7) |
| Spontaneous | 9176 (76.9) | 2118 (75.9) | 10 752 (74.2) |
| Parents Civil Personal Register not reported | 2298 (19.3) | 634 (22.7) | 3195 (22.0) |
| Follow-up from time of diagnosis, median (IQR), y | 10.36 (4.55-16.87) | 5.8 (1.82-8.42) | 8.76 (3.60-15.63) |
Abbreviations: HS, hidradenitis suppurativa; ICD-10, International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; IQR, interquartile range.
Descriptive statistics for the ICD-10 group were identified through the HS ICD-10 diagnosis code in the Danish National Patient Registry; for the proxy group, through the algorithm on procedural codes.
From the total of 14 720 persons, 232 persons diagnosed with HS who were also identified through the algorithm were excluded, leaving a total of 14 488 unique persons.
Total Danish population of 5 781 190 according to Statistics Denmark. First quarter ended on March 31, 2018.
Familial type defined as patients with a first-degree relative with the HS ICD-10 code; spontaneous defined as patients without a first-degree relative with the HS ICD-10 code. In the combined group column, familial is defined as patients with first-degree relatives in either the ICD-10 group or the proxy group.