Analysis of the California In-Home Supportive Services (IHSS) Plus Waiver Demonstration Program. Appendix A. Sample Selection Procedures


The study sample was selected from In-Home Supportive Services (IHSS) recipient listings in 2005. It included anyone in the program as of January 1 of that year, or who entered the IHSS program sometime during 2005. This full sample of recipients is used in analyses describing program recipient characteristics and in analysis of the factors associated with provider selection. Analysis that consider health care use, Medicaid expenditures, or that include health conditions were limited to a subset of IHSS recipients: persons receiving Medicaid through fee for service reimbursement. The exclusion of Medicaid managed care program recipients was necessary because Medicaid claims are not submitted for managed care covered services. The following outlines the steps used to select, screen, and qualify IHSS recipients into the study sample. In combination these assure that we obtained all waiver recipients in each of the target age categories as well as recipients in Advance Pay, and Restaurant Meals vouchers:

  1. All recipients identified as being an active IHSS recipient during any month in calendar year 2005 were tentatively selected into the study (n=408,276).1 Data for both 2004 and 2005 was compiled for these individuals.

  2. The tentatively eligible IHSS recipients included 4,350 pairs of recipients with the same Social Security number, but different IHSS identification numbers. This can occur as recipients are given a new IHSS number if they move from one county to another, even while being an IHSS recipient. There is also the possibility of typographical errors in the identification numbers recorded in the data files. To determine if cases with the same Social Security number were the same individuals, we compared the records on date of birth and whether they had no more than one overlapping month of claims data. Cases meeting these criteria were retained, consolidating the pair under a single common IHSS number. Of the pairs with consistent birthdates, 3,486 had no overlapping claims months, 346 had one overlapping claim month, 301 had more than one overlapping claims month. The remaining 217 pairs had different birth dates. These latter 518 cases were dropped from the study sample.

  3. An additional 42 IHSS recipients had duplicate Department of Developmental Services (DDS) identification numbers that could not be resolved. These cases were also dropped from the IHSS sample.

  4. Within the age group 3-17 any recipient with a Spouse provider (one person in 2005) was excluded because there were too few cases for subgroup analysis. Among those 65 or older, those with “Parent” providers (n=2) were similarly excluded.

  5. The final eligible IHSS sample was sorted into three subgroups: those age 3-17, those age 18-64, those age 65 or more. Individuals changing age group during the calendar year were retained in the original age group.

  6. Advance Pay and Restaurant Meals voucher program recipients were identified using the IHSS Services Assessment. This indicates recipients requesting who are eligible for the program. Such recipients were selected, and the number of participation months was compiled.

  7. IHSS recipients are eligible for Medicaid, but the number of Medicaid claims-records can be under reported for individuals enrolled in a managed care plan. Being in managed care affects the availability and reliability of Medicaid claims data. Managed care organizations are reimbursed on a capitated basis for members, rather than on the basis of utilization. As a consequence services such as hospital, physician, and outpatient services (services included under the capitation payment) may not generate a Medicaid claim. Services (e.g., community-based care, IHSS, and extended nursing home stays) not included under the capitation are not affected. In 2005, 56,1522 (13.9%) study recipients were managed care members for all or part of the year, another. All such cases were list-wise excluded from analyses using Medicaid claims for diagnoses and health care use/expenditures.

  8. IHSS recipients participating in DDS programs were identified by linking the IHSS study sample records with DDS assessment files. This match was limited to persons having Medicaid eligibility.

  9. Classification of waiver and non-waiver recipients was based on the provider relationship information available in the IHSS provider eligibility files. Among those age less that 18, waiver/Residual Program participants are those with a Parent provider. For those 18-64 and 65 or more waiver/Residual Program participants are those with a paid Spouse provider. (Parents of those age 65 or more would also be eligible, but these cases were excluded from the analysis.)2

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