Michael Paterson

Effect of Cost-Sharing on Use of Asthma Medication in Children

OBJECTIVE To examine the effect of cost-sharing on the use of asthma medications in asthmatic children. According to asthma guidelines, children with asthma may require treatment with multiple medications, including controllers and relievers, to achieve optimal control. Although families may be enrolled in drug benefit plans, impediments to access persist in the form of cost-sharing. DESIGN Population-based retrospective cohort study of children by analysis of administrative medication insurance claims data. SETTING Ontario, Canada. PARTICIPANTS A cohort of 17 046 Ontario children with asthma enrolled in private drug plans. Main Exposure We used data on out-of-pocket expenses and reimbursement for medications to classify children as having zero, low (< 20%), or high (> or = 20%) levels of cost-sharing. MAIN OUTCOME MEASURES We examined use of bronchodilators, inhaled corticosteroids, leukotriene receptor antagonists, oral corticosteroids, and combination agents. Multiple linear and logistic regressions compared medication use between cost-sharing groups, controlling for age and sex. RESULTS The annual number of asthma medication claims per child was significantly lower in the high cost-sharing group (6.6) compared with the zero (7.0) and low (7.2) cost-sharing groups (P < .001). Children in the high cost-sharing group were less likely to purchase bronchodilators, inhaled corticosteroids, and leukotriene receptor antagonists compared with the low cost-sharing group (odds ratio, 0.76; 95% confidence interval, 0.67-0.86) and were less likely to purchase dual agents compared with the low cost-sharing group (odds ratio, 0.70; 95% confidence interval, 0.66-0.75). CONCLUSION The cost-sharing level affected the use of asthma medication, with the highest cost-sharing group exhibiting significantly lower use of maintenance medications and newer dual agents.

Hospitalization for Hemorrhage Among Warfarin Recipients Prescribed Amiodarone

Amiodarone inhibits the hepatic metabolism of warfarin, potentiating its anticoagulant effect. However, the clinical consequences of this are not well established. Our objective in this study was to characterize the risk of hospitalization for a hemorrhage associated with the initiation of amiodarone within a cohort of continuous warfarin users in Ontario. We conducted a population-based retrospective cohort study among Ontario residents aged ≥66 years receiving warfarin. Among patients with at least 6 months of continuous warfarin therapy, we identified those who were newly prescribed amiodarone and an equal number who were not, matching on age, gender, year of cohort entry, and a high-dimensional propensity score. The primary outcome was hospitalization for hemorrhage within 30 days of amiodarone initiation. Between July 1, 1994, and March 31, 2009, we identified 60,497 patients with at least 6 months of continuous warfarin therapy, of whom 11,665 (19%) commenced amiodarone. For 7,124 (61%) of these, we identified a matched control subject who did not receive amiodarone. Overall, 56 (0.8%) amiodarone recipients and 23 (0.3%) control patients were hospitalized for hemorrhage within 30 days of initiating amiodarone (adjusted hazard ratio 2.45; 95% confidence interval, 1.49-4.02). Seven of 56 (12.5%) patients hospitalized for a hemorrhage after starting amiodarone died in hospital. In conclusion, initiation of amiodarone among older patients receiving warfarin is associated with a more than twofold increase in the risk of hospitalization for hemorrhage, with a relatively high fatality rate. Physicians should closely monitor patients who initiate amiodarone while receiving warfarin.

Prescription Stimulant Use and Hospitalization for Psychosis or Mania: A Population-Based Study

AbstractSmall studies suggest that prescription stimulants can precipitate psychosis and mania. We conducted a population-based case-crossover study to examine whether hospitalization for psychosis or mania was associated with initiation of stimulant therapy. Between October 1, 1999 and March 31, 2013, we studied 12,856 young people who received a stimulant prescription and were subsequently hospitalized for psychosis or mania. Of these, 183 commenced treatment during 1 of 2 prespecified 60-day intervals (defined as the “risk interval” and “control interval,” respectively) prior to admission. We found that stimulant initiation was associated with an increased risk of hospitalization for psychosis or mania in the subsequent 60 days (odds ratio, 1.86; 95% confidence interval, 1.39–2.56). The risk was marginally higher in patients treated with antipsychotic drugs (odds ratio, 2.06; 95% confidence interval, 1.38–3.28), but remained in patients with no such history (odds ratio, 1.66; 95% confidence interval, 1.09–2.66). One third of subjects received another stimulant prescription after hospital discharge. Of these, 45% were readmitted with psychosis or mania shortly thereafter. We conclude that initiation of prescription stimulants is associated with an increased risk of hospitalization for psychosis or mania. Resumption of therapy is common, which may reflect a lack of awareness of the potential causative role of these drugs.