During the years 2000 through 2002, there were 1,243,504 subjects enrolled in MarketScan Medicare Supplemental and Coordination of Benefits database. A cohort of 487,383 subjects was available for analysis after applying inclusion and exclusion criteria ().
Description of cohort selection, with reasons for exclusions.
On average, each subject had 20 months of follow-up during the study period, with a range of 1 to 24 months, accounting for a total of 9,384,444 person-months of observation. More than 50% of the subjects had the maximum 24 months of follow-up during the study period. provides descriptive information on baseline covariates. The mean age was 73.8 years; 55.5% were women, and more than 75% lived in a standard metropolitan statistical area. Almost one-half of the subjects had a comprehensive Medicare supplemental insurance plan (vs. a preferred provider organization or point-of-service plan with or without capitation) and more than 95% were retired. Nearly 3% of the subjects had a diagnosis of dementia, and 2.1% had a depression diagnosis. Median predicted Medicare spending was $2928 and the range was $1212 to $57,918.
Baseline Characteristics of the Study Cohort (n = 487,383)
Fewer than 14% of the subjects had no prescription drugs during the baseline year. Annual prevalence of potentially inappropriate drugs, defined as 1 or more prescriptions for any of the 74 potentially inappropriate drugs during the baseline year, was 41.9%. Annual baseline prevalences for individual classes of potentially inappropriate drugs ranged from 0% to 14.0%. Hormones, which include systemic estrogens and methyltestosterone, were the most prevalent of the inappropriate drug classes, with 14.0% of the cohort having a prescription. Annual prevalence of inappropriate drug use, excluding hormones, was 35.9%. Use of potentially inappropriate analgesics (propoxyphene, meperidine and pentazocine) (10.0%) also was high.
Of the 487,383 subjects in the cohort, 22,042 (4.5%) experienced a nursing home transition during the 24-month study period. The 1-year cumulative incidence was 26.7 transitions per 1000 subjects.
shows the unadjusted and adjusted risk ratios for nursing home admission for each of the covariates, including the exposure of interest, any inappropriate drug. All variables remained significant after adjustment, although the effects were attenuated. A 31% increase in risk of transition was identified among subjects with any inappropriate drug use during the previous 3 months, as compared with subjects without any inappropriate drugs (, adjusted RR 1.31, 99% CI 1.26–1.36). Use of any other drug (ie, drugs not considered inappropriate) was also associated with nursing home transition.
Relative Risk (RR) of Nursing Home Admission by Drug Use and Baseline Characteristics (n = 487,383 subjects; 9,384,444 person-months of observation)
displays unadjusted and adjusted relative risks of nursing home transition for each class of inappropriate drugs). In the adjusted models for individual drug classes, hormones were the only drug class with a significant protective effect on nursing home transition (adjusted RR 0.74, 99% CI 0.68–0.80). Antipsychotics, antiemetics and analgesics exhibited the strongest effect, with relative risks ranging from 1.97 to 2.03.
Relative Risk (RR) of Nursing Home Admission by Potentially Inappropriate Drug Use Therapeutic Classes (n = 487,383; 9,384,444 person-months of observation)
Because of the controversy surrounding the risks and benefits of hormone replacement therapy in postmenopausal women and of the observed protective effect on nursing home transition, additional analyses were performed excluding hormones as a potentially inappropriate drug. The use of potentially inappropriate drugs, excluding hormones, remained a significant risk factor for nursing home transition (adjusted RR 1.45, 99% CI 1.40–1.51).
To further explore the association of potentially inappropriate drug use and nursing home transition, additional analyses were undertaken for the 3 classes of drugs with the largest effect sizes (ie, narcotic analgesics, antiemetics and antipsychotics). The adjusted relative risks are shown in . For narcotic analgesics and antiemetics, the risk of nursing home transition was similar for inappropriate drugs and other drugs. Inappropriate narcotic analgesics included propoxyphene, meperidine and pentazocine. All other narcotic analgesics were considered to be alternatives to the inappropriate narcotic analgesics. Both inappropriate and alternative narcotic analgesic drug use, compared with no narcotic analgesic drug use, were associated with about a 2.5-fold increased risk of nursing home transition. The relative risk of other narcotic analgesics was statistically significantly higher than inappropriate narcotic analgesics (RR 1.15, 99% CI 1.07–1.23).
Adjusted Relative Risk (RR) of Nursing Home Admission for Selected Drug Classes (n = 487,383)
Similarly, for antiemetic drug use each person-month was categorized with regard to antiemetic use during the previous 3 months: inappropriate antiemetics, other antiemetics and no antiemetics, with this last group as the reference category. There was only 1 antiemetic, trimethobenzamide, which was considered inappropriate. Other antiemetics included dimenhydrinate, dolasetron, dronabinol, granisetron, meclizine, metoclopramide, ondansetron, prochlorperazine and triethylperazine. Both inappropriate and other antiemetic use, compared with no antiemetic use, were associated with about a 2-fold increased risk of nursing home transition, with no statistically significant difference between inappropriate and other antiemetics.
The risk associated with other antipsychotic drugs was greater than that of inappropriate antipsychotic drugs (). Two antipsychotics, mesoridazine and thioridazine, were considered to be potentially inappropriate in the elderly. Other antipsychotics included: aripiprazole, chlorpromazine, clozapine, droperidol, fluphenazine, haloperidol, loxapine, molindone, olanzapine, perphenazine, pimozide, prochlorperazine, quetiapine, risperidone, thiothixene, trifluoperazine, and ziprasidone. Other antipsychotic use was associated with a more than 4-fold increase in the risk of nursing home transition (adjusted RR 4.25, 99% CI 3.98–4.54) whereas inappropriate antipsychotics had only a 2.5-fold increase in risk (adjusted RR 2.50, 99% CI 1.62–3.87). The risk of nursing home admission was statistically significantly greater for other antipsychotics compared with inappropriate antipsychotics (adjusted RR 1.70, 99% CI 1.09–2.64).