We hypothesize that there may be an inappropriate overuse of initial combination therapy in patients with glaucoma and in those who are glaucoma suspects. To test this hypothesis, we examined the British Columbia Population DataBase to determine the frequency of prescription of combination eye drops as initial therapy in glaucoma patients or glaucoma suspects.
The study cohort included all those who visited an ophthalmologist's office between 2004 and 2007. Within the cohort we identified all those who were newly prescribed any ocular hypotensive eye drop. Specifically, we identified those who had been newly prescribed any ocular hypotensive eye drop within 60 days of receiving diagnoses of glaucoma, as defined by having received an international classification for disease code ICD-9 for glaucoma 365.
We used the Population Data British Columbia (POP Data BC) as the main data source for this study. POP Data BC is a provincially linkable database that captures the physician visits (including inpatient procedures); hospital admissions; demographics; and prescription drug use of 4.5 million residents of British Columbia.
Between 2004 and 2007, the percentage of combination therapy as the first ocular hypotensive prescription rose from 12.29% to 18.63%.
The high percentage of combination therapy as initial therapy suggests that ophthalmologists either require additional education in principles of pharmacologic therapy or are unduly influenced by their interaction with the pharmaceutical industry.