Prostaglandin efficacy and safety study undertaken by race (the PRESSURE study)

Latanoprost, travoprost, and bimatoprost are prostaglandin or prostamide-type ocular hypotensive medications, all of which are effective and safe for lowering intraocular pressure (IOP). Most studies with these types of drugs have included patients mainly from European or white ethnic backgrounds; however, some reports have suggested that there is a difference in response between patients of white and African racial heritage. On account of the possibility that drugs may act differently in people of different ethnic background, we decided to study the effectiveness and safety of all 3 drugs in people from various ethnic heritages. Our hypothesis was that there might be a possible ethnic-based difference in IOP-lowering effectiveness between the 3 medications.

This was a prospective randomized investigator-masked multicenter study. Patients newly diagnosed with open-angle glaucoma (primary, pseudoexfoliative, or pigmentary), or whose pressure became elevated after a washout period, were randomized to receive 1 of 3 prostaglandin/prostamide drugs. Assignment of drug was balanced by racial group and study site, and the investigator was masked to the drug used. The patients were requested to self-identify their racial group as White, African, East Indian, Asian, or Hispanic; to minimize the possibility of heterogeneity, all 4 grandparents had to be known to originate from the same group. However, for purposes of analysis, the patients were divided into 2 groups--White or Other. Patients were followed at 2, 6, 12, and 24 weeks; IOP and local side effects were assessed at each visit.

Eighty-three patients were recruited from 9 sites. The mean age of the patients was 61.5 ± 10.5 years. There were no differences in mean age or the distribution of sex between the patients whether examined by the 2 racial groups or the 3 drug groups. There was a highly statistically significant decrease in IOP from baseline to 12 weeks and from baseline to 24 weeks (F = 439.3, P<0.0001; F = 305.94, P<0.0001). There were no differences in treatment effect between the 3 drugs or between the 2 ethnic groups, (P > 0.05 for all comparisons) and there was no interaction between race and drug.

All 3 prostaglandin/amide drugs are highly effective at lowering IOP. No differences in effect between the drugs or between members of different racial groups were detected, although the study sample size was too small to be certain to detect differences, if they existed.