Reduced adherence to therapeutic plans remains a significant global healthcare concern in many chronic diseases, including glaucoma.1 In this study, Newman-Casey et al. evaluated a spectrum of adherence among patients with glaucoma in the Collaborative Initial Glaucoma Treatment Study (CIGTS), finding a statistically significant relationship between medication adherence and glaucomatous visual field progression among the participants randomized to the medication arm of the trial.
Authors found that adherent patients who reported not missing any medication doses had 0.62 dB of visual field loss (ascertained by mean deviation, MD) on average over the seven years of follow-up, consistent with reported rates of age-related changes in MD.2 In contrast, patients who reported missing doses at 1/3 of follow-up visits lost an average of 1.42 dB of MD; those who reported missing doses at 2/3 of visits lost an average of 2.23 dB. Factors associated with non-adherence were of younger age, non-married status, black race, depression, a lower degree of education, and worse baseline MD.
This study showed a significant dose-response relationship between the extent of medication adherence and rate of glaucomatous visual field progression (p = 0.005)
This study showed a significant dose-response relationship between the extent of medication adherence and rate of glaucomatous visual field progression (p = 0.005). However, several issues require further consideration. First, the assessment of medication adherence via self-reported data could have been confounded by overestimation of true adherence. Patients generally overestimate their own adherence when compared to device-measured or pharmacy refill data,3 and the rates of adherence in CIGTS participants exceeded those reported in prior studies.4 Therefore, the magnitude of the reported association may have been underestimated.
Second, visual field progression in non-adherent patients could have been secondary to factors other than medication adherence; association does not equal causation. However, overall this study offers strong secondary analysis of clinical trial data to provide further support for the importance of evaluating patient adherence in glaucoma.