PURPOSE: Therapeutic duplication (TD) in prescriptions is a common cause of inappropriate drug use. This study aimed to determine the prevalence of TD in the Korean ambulatory setting and to determine the patient and prescriber characteristics that were associated with TD of non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics. METHODS: Ambulatory care cases with NSAID/analgesic prescriptions were extracted from the National Health Insurance database for January–March 2011. The Korean TD classification (64 ingredients) was used to define cases of TD. Multivariate logistic regression was used to determine the predictors of TD. The independent variables in the regression model included patient characteristics (sex, age, insurance type, comorbidity, diagnosis, and number of prescribed drugs) and prescriber characteristics (type of medical institution and specialty). RESULTS: Among 21 million patients, we identified 59,636,222 ambulatory care visits with NSAID/analgesic prescriptions; 13.3 % of these cases involved TD. The most frequent duplications were diclofenac/aceclofenac (12.4 % of TDs), diclofenac/talniflumate (11.2 %), and diclofenac/loxoprofen sodium (10.7 %). Male sex, older age, and a Charlson comorbidity index of ≥1 were associated with an increased likelihood of TD. Arthritis, injection administration (OR 3.676, 95 % CI 3.670–3.683), and the number of drugs per prescription were associated with an increased likelihood of TD. Orthopedic and pediatric specialties were associated with an increased likelihood of TD. CONCLUSIONS: This study is the first to determine the prevalence of NSAID TD and the factors that were associated with its occurrence in South Korea. These results may help prevent TD and improve appropriate medication use.
PURPOSE: Therapeutic duplication (TD) in prescriptions is a common cause of inappropriate drug use. This study aimed to determine the prevalence of TD in the Korean ambulatory setting and to determine the patient and prescriber characteristics that were associated with TD of non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics. METHODS: Ambulatory care cases with NSAID/analgesic prescriptions were extracted from the National Health Insurance database for January–March 2011. The Korean TD classification (64 ingredients) was used to define cases of TD. Multivariate logistic regression was used to determine the predictors of TD. The independent variables in the regression model included patient characteristics (sex, age, insurance type, comorbidity, diagnosis, and number of prescribed drugs) and prescriber characteristics (type of medical institution and specialty). RESULTS: Among 21 million patients, we identified 59,636,222 ambulatory care visits with NSAID/analgesic prescriptions; 13.3 % of these cases involved TD. The most frequent duplications were diclofenac/aceclofenac (12.4 % of TDs), diclofenac/talniflumate (11.2 %), and diclofenac/loxoprofen sodium (10.7 %). Male sex, older age, and a Charlson comorbidity index of ≥1 were associated with an increased likelihood of TD. Arthritis, injection administration (OR 3.676, 95 % CI 3.670–3.683), and the number of drugs per prescription were associated with an increased likelihood of TD. Orthopedic and pediatric specialties were associated with an increased likelihood of TD. CONCLUSIONS: This study is the first to determine the prevalence of NSAID TD and the factors that were associated with its occurrence in South Korea. These results may help prevent TD and improve appropriate medication use.