A five-component case-finding protocol using medical and dental Medicaid claims, encounter, and enrollment files identified adults with indicators of IDD. Enrollees who met any of the following criteria and who were enrolled in Medicaid for 11-12 months during 2005 were identified as having a IDD for the purposes of this study: (1) had at least one claim containing an ICD-9 (International Classification of Diseases) diagnosis code on medical claims, 11
representing a medical condition considered to identify a person as having an IDD; (2) had at least one claim while residing in a state facility licensed for the care of people with IDD or an intermediate care facility during 2005; (3) the enrollment file for 2005 indicated that a diagnosis of IDD was made by a health care provider; (4) had a claim for targeted case management provided for IDD; or (5) had a Medicaid enrollment code indicating eligibility for the Home and Community-Based Waiver Program for Mental Retardation (HCBS).
Data for this project were extracted from the Iowa Medicaid Enterprise claims, encounter, and enrollment data for 2001 through 2005. Medicaid eligibility and claims data from 2001 through 2005 were reviewed so as to capture individuals who had a qualifying code for IDD but may not have the ICD-9 code recorded for any medical visits in 2005. If either a qualifying medical diagnostic code, a targeted case management code for IDD, or the Medicaid enrollment for HCBS was recorded during this 5-year period, it was appended to the dental claims for calendar year 2005. This project was approved by the University of Iowa Institutional Review Board for the protection of human subjects.
IDD diagnoses were collapsed into five broad categories: autism, mental retardation, central nervous system disorders, spina bifida, and fetal alcohol syndrome ().12
For those patients who had multiple IDD diagnoses during this time period, the most recent IDD diagnosis was considered to be the enrollee’s primary diagnosis. However, the case-finding criteria demonstrated that many of the Medicaid recipients included in this study did not have an explicit IDD diagnosis on a service claim during the studied period.
ICD-9 diagnosis codes used to identify Medicaid enrollees with IDD
Three demographic variables were included for descriptive analysis: gender, age, and county of residence. Age was defined as the Medicaid recipient’s age in years as of December 31, 2005. Operationally, any Medicaid enrollee 18 years of age or older was considered an adult. Four age categories were established (18–21, 22–44, 45–64, 65 or older). Using the most recent residence, individuals were placed in one of four county categories: metro, urban adjacent to metro, urban nonadjacent to metro, and rural.13
An additional residence variable differentiated between those who were institutionalized and non-institutionalized during this study period. Individuals were considered to be institutionalized if they spent at least six months during 2005 in any of the following mutually exclusive institutional settings: intermediate care facility (ICF), intermediate care facility for people with mental retardation (ICFMR), state facility for people with mental retardation (SMR), or residential care facility (RCF). If enrollees were institutionalized in more than one setting type, they were categorized based on the setting type in which they spent the highest number of months. In cases of a tie, institutions where individuals were more likely to reside with severe disabilities took precedence (i.e., SMR>ICFMR>ICF>RCF).
Medicaid reimburses agencies for the provision of case management services that aid people with IDD in coordinating their health care. Thus, a variable that indicated whether or not the enrollee had at least one Medicaid claim for case management during 2005 was included. In addition, individuals were classified by their specific Medicaid-enrollment category: Temporary Assistance to Needy Families (TANF), based on family income; Supplemental Security Income (SSI), based on severity of disability and income; Foster Care; Institution-eligible, with the overwhelming number being Home and Community-Based Services (HCBS) waiver-eligible; and Other. HCBS, also known as 1915(c) waiver, “allows states the flexibility to develop and implement creative alternatives to placing Medicaid-eligible individuals in hospitals, nursing facilities, or intermediate care facilities for persons with mental retardation.” The preponderance of institution-eligible individuals received the HCBS waiver, which hereafter is designated as HCBS+. Individuals who are eligible for Medicaid in the ‘Other’ category include those who do not fit any of the above program definitions (i.e., those whose medical expenses reduce their income below Medicaid income levels, thereby making them medically needy).
The Iowa dental Medicaid program is a fee-for-service model. Although comprehensive dental services are provided for children, a more limited range of services is available for adults. For purposes of these analyses a dental visit occurred when the dentist submitted a claim to the Medicaid program using Current Dental Terminology (CDT) codes and tooth-related data. Procedures were categorized into broad dental service categories based on CDT codes: preventive (e.g., tooth prophylaxis, topical fluoride, scaling), routine restorative (e.g., amalgam or composite fillings), and complex dental services (e.g., stainless steel crown, root canal, tooth extraction).
An overall dental utilization rate was calculated as the proportion of the study population with at least one paid Medicaid dental claim in 2005. Service-specific utilization rates for preventive, routine restorative, and complex dental services were calculated as the percentage of those with at least one paid Medicaid dental claim who had received the type of service defined for each service category in 2005. Service-specific utilization rates were also calculated for each selected variable (e.g., IDD diagnostic group, age category, county type, institutional setting, case management, Medicaid eligibility group).
Since the entire adult population who met the criteria for IDD was included in the report, no inferential tests were performed in determining statistical differences among categories.