Association of Failed Root Canal Treatment with Dentist and Institutional Volumes: A Population-based Cohort Study in Taiwan.

INTRODUCTION: The volume-outcome relationships in failed root canal treatments (RCTs) are rarely studied. Thus, we aimed to examine the association of failed RCTs with dentist and institutional volumes. METHODS: Ambulatory dental claims (2005-2010) of 1 million beneficiaries randomly selected from the National Health Insurance Research Database of Taiwan were used. This study is a population-based cohort study using a marginal Cox proportional hazards regression model in which the outcome variables cluster around individual patients. A total of 458,557 teeth that received first-ever RCT from 2005 to 2010 and were followed up until the end of 2010 were identified as the tooth cohort. These teeth were aggregated to 244,368 patients, 10,901 dentists, and 7122 institutions for analysis. RESULTS: Dentists in the second, third, and highest quartiles all showed a significantly lower hazard ratio of failed RCTs than those with the lowest case volume, and their adjusted hazard ratios (aHRs) were 0.93, 0.92, and 0.90, respectively. Medical institutions in the second, third, and highest quartiles also showed a significantly lower hazard ratio of failed RCTs than those with the lowest case volume, and their aHRs were 0.93, 0.89, and 0.81, respectively. Teeth with a history of periodontitis also exhibited a significantly higher aHR of failure events. The use of rubber dams significantly reduced the rates of failed RCTs. CONCLUSIONS: Dentists and institutions with high care volumes tended to show good RCT outcomes. Such an effect was prominent and robust among dental institutions.

Demographic and rural-urban variations in dental service utilization in Taiwan.

INTRODUCTION: This study assesses whether demographic and rural-urban variations in dental care service utilization still exist in Taiwan after 15 years of the implementation of universal health insurance coverage, which largely reduces financial barriers to dental care. METHODS: The data analysed in this cohort study were based on a random sample of one million beneficiaries retrieved from Taiwan's National Health Insurance Research Database (NHIRD) in 2005. The follow-up was made between 2005 and 2010. Poisson regression models were used to explore the associations of dental service utilization rates with urbanization and demographic characteristics. RESULTS: The highest and lowest rates of preventive dental care were obtained in people aged 55-64 years (579.2/1000 person-years) and <15 years (178.6/1000 person-years). The corresponding figures for curative care were 1592.0/1000 person-years (<15 years) and 757.2/1000 person-years (35-44 years). Compared with the people living in the least urbanized areas, those from the most urbanized areas presented significantly higher rates of preventive and curative dental services; a greater estimated rate ratio was noted for preventive services than for curative services (1.57 vs 1.42). CONCLUSIONS: The urban-rural disparity in dental care service utilization still exists after 15 years of the implementation of the national health insurance in Taiwan, suggesting that factors other than affordability may play roles in such disparity.

Effects of stroke rehabilitation on incidence of poststroke depression: a population-based cohort study.

OBJECTIVE: To investigate the effects of rehabilitation intervention provided within the first 3 months after admission for stroke on the incidence of poststroke depression (diagnosed according to ICD-9-CM code 296, 309, or 311, or A-code A212 or A219). METHOD: This population-based cohort study examined medical claim data of a random sample of 1 million insured people registered in 2000 in Taiwan. Between 2000 and 2005, there were 7,677 patients admitted as first-time stroke patients. Of these, 1,285 (16.7%) received a rehabilitation regimen within the first 3 months of admission for stroke. The other 83.3% of patients (n = 6,482) belonged to the control group. All study subjects were followed to the end of 2009 to identify any ambulatory treatment for depression as the end point. The incidence density of poststroke depression was calculated assuming a Poisson process. A Cox proportional hazard model was used to estimate the relative risk of poststroke depression in relation to receipt of rehabilitation. RESULTS: Over a 10-year follow-up, 75 patients (5.8%) with rehabilitation and 566 controls (8.7%) developed poststroke depression, representing incidence densities of 11.3 and 18.5 per 1,000 person-years, respectively. After analyses were controlled for potential confounders, rehabilitation was found to significantly reduce the risk of poststroke depression, with a hazard ratio (HR) of 0.57 (95% CI, 0.45-0.73). The effect was greater for men (HR = 0.52; 95% CI, 0.37-0.71), especially for elderly men (HR = 0.45; 95% CI, 0.28-0.71), than for women (HR = 0.69; 95% CI, 0.47-1.02). CONCLUSIONS: Stroke rehabilitation intervention in the first 3 months after admission for stroke may significantly reduce the risk of poststroke depression. Although this beneficial effect appears to be greater for men than for women, clinicians should also be alert for poststroke depression occurring in women.

Risks of Breast and Endometrial Cancer in Women with Diabetes: A Population-Based Cohort Study.

OBJECTIVE: We investigated the overall and age-specific risks of developing breast and endometrial cancer among women with diabetes in a population-based cohort study. METHODS: Women with diabetes (n = 319310) and age-matched controls (n = 319308), selected from ambulatory care claims and beneficiary registry in 2000, respectively were linked to the in-patient claims (2000-2008) to identify admissions due to breast (ICD-9-CM: 174) and endometrial (ICD-9-CM: 182) cancer. The person-year approach with Poisson assumption was used to estimate the incidence density rate. The age-specific hazard ratios (HRs) of above malignancies in relation to diabetes with multivariate Cox proportional hazard regression. RESULTS: The overall incidence density rate of breast and endometrial cancer was estimated at 1.21 and 0.21 per 10,000 patient-years, respectively, for diabetes. The corresponding figures for controls were lower at 1.00 and 0.14 per 10,000 patient-years. Compared with the controls, the covariate adjusted HR for breast and endometrial cancer was 1.42 (95% confidence interval (CI) 1.34-1.50) and 1.71 (95% CI 1.48-1.97), respectively in women with diabetes. Elderly (> = 65 years) diabetes had the highest HR (1.61) of breast cancer, while the highest HR (1.85) of endometrial cancer was observed in diabetes aged < = 50 years. CONCLUSIONS: Diabetes may significantly increase the risks of breast and endometrial cancer in all age stratifications. Health education for strict adherence of cancer screening program in women with diabetes is essential.