• Written By: Gail F. Schwartz, MD

    The authors of this retrospective study sought to determine the persistence rates among glaucoma patients who started taking topical IOP-lowering monotherapy at one hospital in Singapore. They found that persistence rates were very low and worse than in previous studies in Western countries.

    Glaucoma medication persistence is notoriously low. Many persistence and adherence studies have been carried out in the United States and Europe, but data is limited regarding Asian populations and chronic glaucoma medication. Cycling behavior, or restarting after discontinuing, was accounted for in the study design. The study's conclusion that prostaglandin analogs have the best persistence is clinically important and agrees with the results of Western studies. However, the study's design using retrospective claims-based analysis in a hospital setting has limitations.

    The researchers retrospectively examined pharmacy database information for 2,781 patients who started taking a single IOP-lowering medication during a one-year period. Most of the patients were Chinese (81.1 percent) or Singaporean residents (85.4 percent). Pharmacy dispensing records were traced for three years from the date of first prescription. A patient was defined as persistent if he or she was prescribed the same medication before or within 90 days after the previous prescription had lapsed during this period.

    After one year, only 22.5 percent of patients persistently received the same therapy, which decreased to 11.5 percent after three years. Prostaglandin analogs had better persistence rates at one year compared with other medications (P < 0.001).Younger age, being Singaporean, not receiving government subsidies and receiving unilateral therapy each were significantly linked to lack of persistence at one year.

    The authors conclude that the poor persistence found in the study shows that patients frequently change or discontinue their treatment regimen, with potential effects on therapeutic effectiveness. They believe these results are reflective of the persistence of glaucoma patients in this region and fear that persistence may be even worse in less developed Asian countries. The results indicate that strategies are urgently needed to improve persistence in this population. They say that prospective cohort studies investigating reasons for lack of persistence, including the effect of glaucoma type and severity, should be conducted.