Constructing Matched Groups in Dental Observational Health Disparity Studies for Causal Effects.

INTRODUCTION: Electronic health record (EHR) systems provide investigators with rich data from which to examine actual impacts of care delivery in real-world settings. However, confounding is a major concern when comparison groups are not randomized. OBJECTIVES: This article introduced a step-by-step strategy to construct comparable matched groups in a dental study based on the EHR of the Willamette Dental Group. This strategy was employed in preparation for a longitudinal study evaluating the impact of a standardized risk-based caries prevention and management program across patients with public versus private dental insurance in Oregon. METHODS: This study constructed comparable dental patient groups through a process of 1) evaluating the need for and feasibility of matching, 2) considering different matching methods, and 3) evaluating matching quality. The matched groups were then compared for their average ratio in the number of decayed, missing, and filled tooth surfaces (DMFS + dmfs) at baseline. RESULTS: This systematic process resulted in comparably matched groups in baseline covariates but with a clear baseline disparity in caries experience between them. The weighted average ratio in our study showed that, at baseline, publicly insured patients had 1.21-times (95% CI: 1.08 to 1.32) and 1.21-times (95% CI: 1.08 to 1.37) greater number of DMFS + dmfs and number of decayed tooth surfaces (DS + ds) than privately insured patients, respectively. CONCLUSION: Matching is a useful tool to create comparable groups with EHR data to resemble randomized studies, as demonstrated by our study where even with similar demographics, neighborhood and clinic characteristics, publicly insured pediatric patients had greater numbers of DMFS + dmfs and DS + ds than privately insured pediatric patients. KNOWLEDGE TRANSFER STATEMENT: This article provides a systematic, step-by-step strategy for investigators to follow when matching groups in a study-in this case, a study based on electronic health record data. The results from this study will provide patients, clinicians, and policy makers with information to better understand the disparities in oral health between comparable publicly and privately insured pediatric patients who have similar values in individual, clinic, and community covariates. Such understanding will help clinicians and policy makers modify oral health care and relevant policies to improve oral health and reduce disparities between publicly and privately insured patients.

Identifying communities with low dentist supply in California.

OBJECTIVES: This study estimates the supply and geographic distribution of dentists in California and examines the community characteristics associated with supply of dentists. METHODS: The number of practicing dentists was estimated from American Dental Association data on licensed dentists in California. Each dentist's address was geocoded and matched to a Medical Service Study Area (MSSA). Dentist-to-population ratios were computed, and the association between dentist supply and community characteristics was analyzed in regression models. RESULTS: Approximately 20 percent of California communities may have a shortage of dentists. Two-thirds of dental shortage communities are rural. Communities with a lower supply of dentists have higher percentages of minorities, children, and low-income persons. Minority dentists were more likely to practice in minority communities. CONCLUSIONS: Geographic maldistribution of dentists may contribute to poor access to dental care in many communities, especially in rural, low-income, and minority communities. Minority dentists are more likely to practice in minority communities, but are a small portion of the dental workforce.