One-sided versus 2-sided statistical analysis of the safety and efficacy of intracameral moxifloxacin to prevent post-cataract endophthalmitis

I read the study by Melega et  al.1 I disagree with their use of the 1-sided chi-square or Fisher exact test. The incidence of endophthalmitis reported in the study was 0.05% (1/1818; it should be 0.06%) in the moxifloxacin-treated group and 0.38% (7/1822) in the control group. The 1-sided Fisher exact test yields a P value o f 0.035, which is less than 0.05 and statistically significant. However, with the 2-sided Fisher exact test, the P value is 0.07 and not statistically significant. The chi-square test gives similar results.
Source: Journal of Cataract and Refractive Surgery - Category: Opthalmology Authors: Tags: Letters Source Type: research