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Objective The authors sought to determine the incidence of lithium-induced hypothyroidism in a population-based cohort of older adults beginning lithium therapy and thereby to inform clinical guidelines on the frequency of monitoring necessary in this group. Methods The authors conducted a population-based observational cohort study using four administrative databases that contained information on over 1.3 million older adults in Ontario who receive universal healthcare coverage in terms of physician services, drugs, and hospitalizations. Over an 18-month period, they studied adults age ≥65 who were newly prescribed lithium or valproate, monitoring subjects for initiation of T 4 therapy (as a proxy for hypothyroidism) while they continued their lithium use. Results The authors identified 1,705 new users of lithium and 2,406 new users of valproate with similar baseline characteristics. Lithium users were significantly more likely to be treated with T 4 than were valproate users. The rate of T 4 treatment per 100 person-years was 5.65 in the lithium group and 2.70 in the valproate group. Conclusion T 4 treatment was initiated in almost 6% of lithium-treated patients, suggesting the possibility that hypothyroidism developed twice as frequently among these patients as would be expected among a mixed-age population. Increased vigilance and continued monitoring of thyroid functioning for at least 2 years is necessary in older adults beginning lithium therapy.

Objectives. We sought to determine whether more comprehensive risk-adjustment models have a significant impact on hospital risk-adjusted mortality rates after coronary artery bypass graft surgery (CABG) in Ontario, Canada. Background. The Working Group Panel on the Collaborative CABG Database Project has categorized 44 clinical variables into 7 core, 13 level 1 and 24 level 2 variables, to reflect their relative importance in determining short-term mortality after CABG. Methods. Using clinical data for all 5,517 patients undergoing isolated CABG in Ontario in 1993, we developed 12 increasingly comprehensive risk-adjustment models using logistic regression analysis of 6 of the Panel’s core variables and 6 of the Panel’s level 1 variables. We studied how the risk-adjusted mortality rates of the nine cardiac surgery hospitals in Ontario changed as more variables were included in these models. Results. Incorporating six of the core variables in a risk-adjustment model led to a model with an area under the receiver operating characteristic (ROC) curve of 0.77. The ROC curve area slightly improved to 0.79 with the inclusion of six additional level 1 variables (p = 0.063). Hospital risk-adjusted mortality rates and relative rankings stabilized after adjusting for six core variables. Adding an additional six level 1 variables to a risk-adjustment model had minimal impact on overall results. Conclusions. A small number of core variables appear to be sufficient for fairly comparing risk-adjusted mortality rates after CABG across hospitals in Ontario. For efficient interprovider comparisons, risk-adjustment models for CABG could be simplified so that only essential variables are included in these models.

Background:Coronary artery disease is a leading cause of heart failure. Statins are efficacious drugs for the primary and secondary prevention of coronary heart disease, but their value in persons with heart failure remains unknown. Methods:We performed a population-based retrospective cohort study involving the entire province of Ontario, Canada, restricting participants to those aged 66 to 85 years who were free of cancer and who survived at least 90 days following hospitalization for newly diagnosed heart failure. The primary study outcome was the risk of death from all causes, nonfatal acute myocardial infarction, or nonfatal stroke among persons newly dispensed statins (n=1146) relative to those who were not (n=27682). Results:Themeanageofallparticipantswas76.5years, and half were women. During the 7-year study period, death, acute myocardial infarction, or stroke occurred in 217statinrecipients(13.6per100person-years)vs12299 nonrecipients (21.8 per 100 person-years; adjusted hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.630.83). Most of the benefit from statins was related to a reduction in all-cause mortality (adjusted HR, 0.67; 95% CI,0.57-0.78).Nosignificantreductionwasseenforsubsequent myocardial infarction (adjusted HR, 0.81; 95% CI,0.63-1.03)orstroke(adjustedHR,0.81;95%CI,0.531.25). Conclusions: Statin use is associated with a lower risk of death among seniors newly diagnosed as having congestive heart failure. While statin use has been previously shown to be efficacious in patients with coronary heartdiseaseandstroke,wecouldnotcontrolforallprognosticriskfactorsinthepresentstudy,includingleftventricular ejection fraction and serum lipid levels. Better evidence can direct clinicians about which patients with heart failure might benefit from these drugs. Arch Intern Med. 2005;165:62-67