Study Characteristics
Due to the absence of published RCTs, we used 9 cohort studies7,19,21,24–28,31 and 6 case-control studies8,20,22,23,29,30 in our systematic review and
meta-analysis. The study characteristics are shown in Table 1. All
studies were conducted in Asia and Europe. More precisely, 10 studies7,8,19–23,29–31 were conducted in Turkey, 3 studies25,27,28 in Finland, one study 24 in
United Kingdom and one study 26 in Switzerland.
Regarding gender, in 7 studies 7,8,19,24,28,30,31 the
population was mixed, in 5 studies 20–23,29 females
only and in 3 studies 25–27 males only. In all
studies isotretinoin was administered orally. In 7 studies8,19,23–27 the dosage of isotretinoin was steady
during therapy with range between studies 0.5-1 mg/kg/day, and in one
study 22 the dosage was 120-150mg/kg/day. In 5 studies7,20,21,29,31 increasing dosage was used, while in 2
studies 28,30 the dosage was not mentioned. In five
studies 22,23,28,30,31 the treatment duration was 3
months, in 2 studies 19,24 4 months, in one study8 5 months and in 2 studies 20,21 6
months. In 4 studies 7,25,27,29 the treatment duration
was dependent to disease progression. In only one study26 the duration was 5 days, but in a previously
treated population with isotretinoin for acne vulgaris.