Setting and location

The REP was established in 1966 by Dr Leonard T. Kurland, as a collaboration between medical care providers in Olmsted County, Minnesota, to share medical record information for research. Each medical care provider in Olmsted County uses a unit (or dossier) medical record system where all data collected for a person are assembled in one place.13 The REP links these medical records to unique persons residing in the community, and maintains an electronic index of diagnoses and procedures from these records, including hospitalisations, office visits, emergency room visits, surgical procedures and drug prescriptions. The REP allows investigators to follow subjects across all local medical facilities, regardless of where the care was delivered or of insurance status. Thus, using the resources of the REP, investigators can conduct long-term, population-based studies of disease incidence, prevalence, risk and protective factors, outcomes, health services usage and cost-effectiveness. Over 40 medical care providers have participated in this unique collaboration since 1966, and this resource has been used extensively in research studies that have led to over 2400 scientific publications.13 The population of Olmsted County is representative of the population of Minnesota, of the Upper Midwest and of a large segment of the entire US population.14 Details regarding the history of the REP and a list of studies that have used the REP are available at the REP website: http://rochesterproject.org/

Recruitment of dental practitioners

Although a wide range of community healthcare providers have partnered to share their data through the REP, local dental practitioners have not historically participated in this collaboration. However, in July 2008, ABC (Chair of the Department of Dental Specialties at Mayo Clinic) conducted a mailed survey among 96 dentists in over 40 practices in southeastern Minnesota. The survey is included in Appendix A, and was designed to assess the interest of the dentists in different types of research. Overall, 45 (47%) dentists responded to the survey, and 42 indicated they were either ‘somewhat’ or ‘very’ interested in research regarding the impact of oral health on general health. With this preliminary information, ABC began an effort in 2009 to develop partnerships with the many interested dental practitioners in the community. He approached the interested dentists through individual meetings, and obtained initial commitments from two dentists in the community to join the REP as new research partners.

Following ABC's initial efforts, the REP team developed specific processes for each new dentist to share data with the REP for research purposes. The first step in each partnership was to establish a data sharing contract and a Health Insurance Portability and Accountability Act (HIPAA) business associate agreement between the dental practitioner and the REP. These agreements explicitly state the rules under which data may be used for research. In particular, the data sharing agreements do not allow the REP, or any investigators that use the REP, to provide details regarding the individual dental practices that participate in the REP (eg, number and types of providers, specific types of services provided, etc). These agreements are in place to ensure that comparisons are not made between practices and that no practice may be singled out as superior or inferior to another practice. Once these agreements were established, dental care providers were then required to obtain Minnesota Research Authorization from their patients.15

Minnesota state law requires that healthcare providers obtain authorisation to use health records for research from all patients who received medical care after 1 January 1997 (Minnesota State privacy law—Statute 144.335, 1997). According to the law, two attempts to obtain this authorisation from each participant must be completed in writing, with at least 60 days between attempts. If the patient gives explicit authorisation, or does not respond after two attempts, then the record can be used for research purposes. Finally, parents must sign the authorisation forms for their children (<18 years), and all children must sign forms for themselves once they become adults (≥18 years). All providers that participate in the REP have implemented systems to comply with this law, and authorisation rates are high. In 2000, only 1.7% of the population refused to allow any of their records to be used for research, and that percentage increased only slightly in 2010 to 2.4%.15 This legal requirement represents a significant burden to providers, and remains the single most important barrier to using oral health data for research in our community.

The first community dentist joined the REP in 2011, and implemented the process for obtaining Minnesota Research Authorization beginning in August 2011. Data were first obtained from this practice in March 2013, and were matched to the medical records of persons included in the existing REP research infrastructure. As of May 2015, eight dental practices (30 clinicians) had signed contracts with the REP, collected Minnesota Research Authorization from their patients and began sharing data with the REP. Data from the dental providers are updated annually, and are matched to existing persons in the REP using previously described procedures.16 Complete data from all practices are available beginning in 2012.

Obtaining data from the dental practices

The REP Administrator (LK) and the REP Programmer (CB) met with dental staff to discuss the type of billing system and the type of dental record used by the practice. The REP team provided a list of desired fields (demographics, billing codes and dates of service) and discussed with office staff the process by which they would record Minnesota Research Authorization status in their systems. All practices chose to record research authorisation as a custom procedure. All participating dental practices used electronic health records, and all captured patient demographic information electronically and billed for their services using American Dental Association (ADA) Current Dental Terminology (CDT) electronic billing codes. However, the type of dental record and billing system varied from site to site. Four sites used Dentrix, three sites used Eaglesoft and one site used a proprietary record. Extraction of the data differed depending on the type of system employed by the practitioner. All data were downloaded at the dental offices by the REP Programmer (CB) on a secure drive, and transported immediately to an REP secure server. Data format differed depending on type of dental record and on the billing system that was used. Data in a comma-separated values (csv) format were simple to work with electronically; however, data were only available in portable document format (pdf) for four sites. These data needed to be extracted via a time-consuming pdf-splitting process before they could be integrated into the REP systems.

Linking dental records to the REP research infrastructure

All data were standardised prior to incorporation into the REP. Research authorisation status was also extracted from the procedure file and applied to the patient records. ADA categories and CDT code descriptions were applied as part of the standardisation process. Linking medical and dental records was accomplished via the usual REP linkage procedures that have been described previously.16 Briefly, patient records were matched electronically via multiple rounds of matching, where the first three rounds of matching were based on a complete match between the records on at least four of the following data points: patient first and last name, date of birth, sex and social security number. Successive rounds of matching used less stringent criteria, including fuzzy matching of name substrings, use of middle initial and Soundex.17 Matches of less than four data points relied on address or name history for corroboration. If a match had too few data points for a confirmed match, the data were stored but not incorporated into REP until additional demographic data on the patient are acquired.

Completeness of the demographic information varied from site to site. For example, some sites captured full names, sex, dates of birth and social security numbers, but other sites captured only patient name and address. Missing data were a significant barrier to linkage. However, ∼89% of all dental patients matched to a person in the REP system.

Type and completeness of dental data

The type and the completeness of the data in the dental records vary substantially across dental practices, and are highly dependent on the needs of the dentist and the individual patient. Some of the records include a detailed medical history and extensive dental details. Other records are brief and limited only to the reason for the visit. Therefore, it is not possible to electronically obtain all of the pertinent details from these records in a standard way that is simple to access for all research studies. However, these limitations are common to medical records as well, and the goal of the REP research infrastructure is to provide complete electronic information when such information is consistently collected and available (eg, demographic data, billing code information, visit dates and location of the dental record). This information then serves as an index to direct a researcher to the areas of the dental record that are most likely to contain the information needed for a particular study.

For example, if a researcher is interested in conducting a study related to dental implants, the REP staff will provide the researcher with a list of patients with a billing code for dental implants, the date of the service and the name of the practice at which the implant was performed. The REP staff will then arrange a time for the researcher to visit the dental practice and review the dental record to abstract the pieces of information pertinent to the study. All of the dental partners have agreed to facilitate these visits and to provide space for a visiting researcher. Therefore, all information in the dental records is accessible to an interested researcher. However, as the types and amount of data collected differ dramatically from practice to practice, it is often necessary for a researcher to review all possible dental and medical records to collect the relevant information for the study.

Number of patients with dental data

Using the REP Census, we identified all persons who resided in Olmsted County, Minnesota, at any time from 1 January 2013 through 31 December 2013.16 We then identified all persons who received a dental service of any kind between 2012 and 2014. The proportion of persons for whom dental data were available is presented separately by sex, four broad age groups (0–18, 19–39, 40–64 and 65+ years), race (white, black, Asian and other race) and ethnicity (Hispanic). χ² tests were performed to determine whether the availability of dental information differed by these characteristics. In addition, among persons for whom dental data were available, we describe the frequency of various types of dental services, separately across the four age groups.

As of 14 April 2015, 46 973 patients have been asked to sign Minnesota Research Authorization for their dental records, and 42 745 (91%) have granted authorisation for use of their dental record for research. The amount of dental data varies across practices, but all practices have shared at least 3 years of data (2012–2014). Data consist of demographic information (name, sex, date of birth) and dental service data. Dental service data are coded using the ADA and CDT codes, and dates of each service are also available. Between 2012 and 2014, 31 750 patients received nearly 477 000 dental services. Persons with at least some dental data in the REP are similar to persons who do not yet have dental data in the REP (table 1); however, male patients, patients between the ages of 19–39 years, and non-white patients are less likely to have dental data. The median number and types of services received during this time frame are shown by age group in table 2. Diagnostic services were the most common service for all age groups; however, other services differed by age. For example, 74% of children (0–18 years) had at least one preventive service code compared with 50% of older adults (65+ years). Conversely, older adults (65+ years) were more likely to have a removable service code (47%) compared with only 2% of children (0–18 years).

Strengths and limitations

A major strength of this expansion is the availability of linked medical and dental health data for over 30 000 individuals. This large sample size provides a unique opportunity to address a wide range of oral health research questions. A limitation of this project is the relatively small number of dental partners participating in the REP. In 2014, more than 40 private dental practices were located in Olmsted County; however, only eight currently participate in the REP. We are not able to compare the type of dental data available for these eight practices to dental data for the entire county, because such data are not available. It is possible that the data available from these eight practices are not representative of the type of dental care received by all community members. In addition, the proportion of persons of black race or Hispanic ethnicity with available dental data is lower than the proportion of persons with available medical data, indicating that we are disproportionately missing dental data on our racial/ethnic minority population. Further efforts to engage other community dental practitioners will provide a more complete picture of the oral health for the entire community. In particular, Olmsted County has a single oral health service which provides free or low-cost dental services to the underinsured and uninsured local population, and discussions are ongoing with this service for inclusion in the REP.