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Polypharmacy and Hospitalization Among Older Home Care Patients

^a Division of Geriatric Medicine, Saint Louis University Medical School, Missouri
^b Geriatric Research Education and Clinical Center, Saint Louis VA Medical Center, Missouri
^c Midwest Research Institute, Kansas City, Missouri

Joseph H. Flaherty, St. Louis University Medical Center, Geriatrics Division, 1402 S. Grand, Rm. M238, St. Louis, MO 63104 E-mail: flaherty{at}slu.edu.

William B. Ershler, MD

	Abstract

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Background. One of the major goals of home care is the prevention of hospitalization. The objective of this study was to examine the relation between medication use (number, type, and inappropriateness) and hospitalization among home care patients older than 65 years.

Methods. A retrospective chart review of 833 discharged older home care patients was performed. These patients were consecutive discharges from a single home care agency who either (a) returned to independent self-care or care of the family (S/F Care group) or (b) were admitted to the hospital (Hospitalized group). Medication assessment within these two groups included total number of medications (prescription and nonprescription); degree of polypharmacy (percentage of patients taking 5 or more, 7 or more, and 10 or more medications); and prevalence for different types of medications, including different types of inappropriate medications. Inappropriate medications were designated according to a list that was previously developed through a modified Delphi consensus technique by a panel of 13 experts in geriatric pharmacology and has been utilized in other studies. Student's t test was used for continuous variables and chi-square test was used for categorical variables to evaluate for differences between the S/F Care group and the Hospitalized group ( p <.05). For comparisons of types of medications, p < .01 was used for significant differences, because of the high number of comparisons made.

Results. Of 833 discharges, 644 (77.3%) returned to self-care or care of the Family (S/F Care group) and 189 (22.7%) were hospitalized. The Hospitalized group, compared with the S/F Care group, was taking a higher number of medications (mean ± SD: 6.6 ± 3.9 vs 5.7 ± 3.4, p = .004), and had a higher percentage of patients taking 7 or more medications (46% vs 26%, p = .002) and 10 or more medications (21% vs 10%, p = .005), but not 5 or more medications. Only three types of medications were more commonly used among patients in the Hospitalized group than among patients in the S/F Care group: clonidine (4.2% vs 1.1%, p = .004); mineral supplements (23.8% vs 14.8%, p = .003); and metoclopramide (5.8% vs 2.0%, p = .006). The Hospitalized group had a lower percentage of patients taking inappropriate medications than did the S/F Care group (20% vs 27%, p = .040), but none of the types of inappropriate medications was used more often in either group.

Conclusions. This study shows a relationship between high levels of polypharmacy and hospitalization. Although it cannot be determined from this study whether a higher number of medications was an indicator of sicker patients at risk for hospitalization, or whether a higher number of medications might have directly led to hospitalization, polypharmacy should still be considered a marker for older home care patients for whom prevention of hospitalization is the goal.

THE home care component is the fastest growing portion of the Medicare budget ⁽¹⁾. Factors affecting this increase include the aging of the population, shorter hospital stays, and an emphasis on outpatient care. For many years, home care has been "under the gun" to prove itself, and one way it has done so is by preventing hospitalization, a high-cost, high-morbidity outcome. Many older studies on home care had difficulty showing cost-effectiveness for outcomes such as hospitalization because home care services were not "targeted." That is, many people who received home care services may not have actually needed them, or they may have received more services than they needed given how sick they were ⁽²⁾. Thus, any information about home care patients who become hospitalized while receiving home care services compared with those who are not hospitalized would help this goal of targeting to prevent hospitalization ⁽³⁾⁽⁴⁾. Previous studies have shown that home care patients with congestive heart failure ⁽⁵⁾, lung disease ⁽⁶⁾, and depressive symptoms ⁽⁷⁾ are at high risk for hospitalization and that focused care can reduce rates of hospital admission. This study examined the relationship between medication use (particularly polypharmacy and types of medications) and hospitalization among older home care patients.

	Methods

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A retrospective chart review of persons discharged from the Visiting Nurse Association (VNA) Home Care Agency (HCA) was undertaken. The year this study was performed, the VNA was one of the largest nonprofit HCAs in St. Louis. In 1994, it conducted more than 137,000 visits, and more than 70% of the agency's patients were over 65 years of age. The population in this study was a typical home care population in that the majority of its patients were elderly, similar to the populations of other databases at that time ⁽⁸⁾.

Subjects were (a) consecutive discharges from May 24, 1994 to November 30, 1994; (b) over the age of 64; and (c) discharged because the patient had completed home care services and returned to S/F Care or had been hospitalized. Charts of patients who changed agencies, moved, went to a nursing home, or died were not reviewed. Data on demographics (age and gender) were collected through the VNA computer database. Data on referral source (i.e., site from which patients entered home care) were unavailable from the database.

Concerning data on diagnosis, previous studies of health care utilization have usually used a small number of broad categories such as "pulmonary," "cardiac," "neurologic," "diabetes," "urologic," "neoplastic," and "other" ^(9)(10). To describe the population in this study more precisely, a detailed list of diagnoses was developed by three of the authors (JF, HP, and JM) on the basis of primary ICD-9 (International Classification of Disease) diagnosis for which the patient was referred ⁽¹¹⁾. Table 1 shows the diagnostic categories, and the appendix shows how these categories were developed based on the ICD-9 diagnosis.

The medications were categorized by one of the authors (JF, who was blinded to discharge status of the patients) according to the product category index in the 1995 Physicians' Desk Reference (PDR; Table 2 ) ⁽¹²⁾. In some cases, (in order to be as descriptive as possible), if only one type of medication was listed in a particular category—for example, warfarin (but not heparin) under the category of "anticoagulants," or nitrates under the category of "vasodilators, coronary"— then that medication was listed in the table instead of the category. Otherwise, each category listed in Table 2 can be found in the product category index of the 1995 PDR. Medications were not included in these categories if they were inappropriate medications as defined below and in Table 3 .

For calculating the total number of medications for each patient, we determined the following guidelines before the study began: (i) total number of medications included prescription and nonprescription (OTC) medications; (ii) "routine" and "as needed" medications were not differentiated; (iii) each medication that the patient was taking was counted as one. For example, if a patient was taking two different types of diuretics, each diuretic was counted as one medication. The only exceptions to this were if a patient was on more than one vitamin, then they were all counted together as one medication; and if a person was on insulin, no matter how many different types, it was counted as one medication; and (iv) pharmaceuticals not counted were all types of nasal sprays, artificial saliva formulations, topical medications, and any nutritional supplement such as a protein shake.

To compare prevalence of medication use between the Hospitalized group and the S/F Care group, we calculated prevalence as [Number of patients in each group who were taking x (where x = category of medication) ÷ total number of patients in that group] x 100. For example, for prevalence of diuretic use, 86 patients in the hospitalized group were taking diuretics out of a total of 189 patients in that group: 86/189 x 100 = 45.5% (see Table 2 ). Additionally, we compared our data with data from the published literature on two separate elderly populations—nursing home patients and community dwellers. Studies that used similar methods, particularly concerning the list of inappropriate medications, were chosen for comparison ^(14)(15)(16).

Data Analysis
The following variables were compared between patients in the S/F Care group and the Hospitalized group: age; gender; mean total number of medications; percentage of patients taking 5 or more, 7 or more, and 10 or more medications; percentage of patients taking each type of medication; and percentage of patients taking at least one inappropriate medication. Instead of choosing an arbitrary number to define polypharmacy for home care patients, we chose three different cutoff points based on previous studies ^{(15)(17)(18)(19)}: 5 has been used in community-based and outpatient studies ^(17)(18); 7 is the average number of medications taken by patients in nursing homes ⁽¹⁵⁾: and 10 is the number of medications at which risk of adverse drug events approaches 100% ⁽¹⁹⁾.

To evaluate for differences between the S/F Care group and the Hospitalized group, we used Student's t test (two-tailed) for continuous variables and chi-square test for categorical variables ( p < .05). For comparisons among types of medications, we used p < .01 for significant differences because of the high number of comparisons made (Table 2 and Table 3 ). Statistical analyses were performed using a commercially available statistics package (Statistica, Statsoft, Tulsa, OK).

	Results

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Of 833 discharges from home care, 189 (22.7%) were hospitalized (Hospitalized group) and 644 (77.3%) returned to independent self-care/care of the family (S/F Care group). There were no differences between the two groups in age (77.1 ± 7.3 vs 77.9 ± 7.5, p = .301) or percentage of women (65.1% vs 63.0%, p = .571). Table 1 lists the primary diagnoses of patients for the whole group, in order of decreasing frequency. For the majority of diagnostic categories, the two groups did not differ. However, there was a higher percentage of patients in the S/F Care group with arthritis/connective tissue disorder and hypertension and a lower percentage of patients with cancer.

The Hospitalized group, compared with the S/F Care group, was taking a higher average number of medications (mean ± SD: 6.6 ± 3.9 vs 5.7 ± 3.4, p = .004). The percentage of patients taking 5 or more medications did not differ between the two groups (66.1% vs 58.9%, p = .068), but was higher in the Hospitalized group compared with the S/F Care group for 7 or more medications (46.0% vs 26.2%, p = .002) and 10 or more medications (21.2% vs 10.0%, p = .005).

Table 2 details the prevalence of medication use in order of decreasing frequency. Five of the top 10 medications used (salicylates [mainly aspirin], H2 blockers, laxatives, vitamins, and acetaminophen) are all available without a prescription. There was a difference in prevalence between the two groups for only 3 of the 40 categories/types of medications: clonidine, mineral supplements, and metoclopramide. These medications were more commonly used by patients in the Hospitalized group (Table 2 ).

With regard to the specific types of inappropriate medications used, we found no significant differences in prevalence between the two groups (Table 3 ). However, the percentage of patients who used at least one inappropriate medication was higher in the S/F Care group compared with the Hospitalized group (27% vs 20%, respectively, p = .040) (data not shown in table).

In comparison to other studies, the home care population falls between the nursing home and community-dwelling populations in the average number of medications taken and prevalence of inappropriate medications (Table 4 ). On further comparison (data not shown), propoxyphene use was higher in the home care population (16.2%) compared with the nursing home population (11.7%) ⁽¹⁵⁾ and both of the community-dwelling populations (0.5% and 4.8%) ^(14)(16). On the other hand, benzodiazepine use was lower in the home care population (3.5%) than the nursing home population (12.7%) ⁽¹⁵⁾ and the two community-dwelling populations (5.1 and 6.0%) ^(14)(16).

	Discussion

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The types of medications seemed to be less important between the two groups. The prevalence of medication use for the vast majority of categories or types of medications (37 out of 40) was not different between the two groups. We also found that no one particular type of inappropriate medication was more commonly used by either group. However, the S/F Care group as a whole had a higher percentage of patients taking at least one inappropriate medication.

The clinical significance of these findings is twofold. First, a higher number of medications among the Hospitalized group could have resulted in more adverse drug events (ADEs), drug–drug interactions, and poorer compliance, which contributed to the hospitalization ^{(20)(21)(22)(23)(24)}. As previous work has shown ^(19)(20), one of the strongest factors associated with ADEs is the number of drugs taken, and the risk of ADEs approaches 100% when the number of medications reaches 10 ^(19)(20). This study is consistent with past findings. Because ADEs have been shown to be associated with hospital admissions ^(20)(21), as well as excess health care costs, longer hospital stays, and attributable mortality ⁽²²⁾, identifying patients at greatest risk for ADEs has important implications.

Second, a higher number of medications could be an indicator of sicker patients. Rosholm and Christensen have shown a relationship between drug use and self-reported health and suggest that limited drug use is a proxy for good health ⁽²⁵⁾. The present study suggests that the converse may also be true—higher drug use is a proxy for poor health. As noted in Table 4 , the average number of medications and the percentage of inappropriate medications increased from community dwellers to home care patients to nursing home patients. This finding is consistent with the assumption that home care patients are intermediate in their medical needs compared with the other two groups of patients.

Thus, polypharmacy among home care patients may be an identifiable risk factor for subsequent hospitalization that is amenable to intervention. Future studies will need to determine if a targeted intervention to reduce medications among home care patients results in improved outcomes.

Although the results of this study provide compelling evidence for further investigations concerning polypharmacy, ADEs, and home care patients, several limitations should be noted. First, the population studied is from a single home care agency serving one geographic area, and the results may not be generalizable to other agencies or locations. Also, we did not review charts of patients who had moved or changed agencies, who were closed to home care because of nursing home admission, or who had died. Patients who moved or changed agencies could not be tracked, but this was a rare event. Prevention of nursing home admission using home care is a broad separate topic related to different factors than those related to prevention of hospital admission ⁽²⁾, and thus, they were not included. Lastly, the number of patients who died during the study was 47, which was too small for comparison.

Another limitation of the study is that the data considered the use of prescription and nonprescription medications together, not separately. It would have been helpful to distinguish between these two uses, but we did not believe it was necessary because the focus of this study, as in other studies ^(14)(19), was total number of medications. Interestingly, 5 of the 10 most commonly used medications in our study are obtainable without a prescription. Nonprescription drug use among the elderly is sevenfold that of the general adult population compared with twofold for prescription drugs ⁽²⁰⁾. This gap could continue to grow; one study of 4509 elderly individuals showed an increase in average number of drugs per person from 1978–1979 to 1987–1988, primarily due to use of nonprescription drugs ⁽²⁶⁾. Perhaps the most appropriate site to discover the use of nonprescription medications is in the home. In fact, medication lists collected in the home have been found to be more accurate than those collected in the office-based setting or those based on hospital discharge summaries ⁽²⁷⁾.

There are some discrepancies in our findings. The first is that the diagnostic codes did not correlate with the prevalence of medication use. For example, patients in the S/F Care group were more likely to have a diagnostic code for arthritis/connective tissue disorder, but did not have a higher prevalence of nonsteroidal anti-inflammatory drugs prescribed compared with patients in the Hospitalized group. This was most likely due to the fact that only one primary diagnostic code (the one describing the reason for the initial home care referral) was reported, whereas all prescribed medications were reported. Thus, a direct comparison between diagnosis and medications was not possible. Similarly, data on other potential markers of risk for hospitalizations, such as functional status, caregiver status, other diagnoses, or frequency of home visits, were not collected. Future studies on the risk of hospitalization will need to include these factors as well as polypharmacy.

Finally, we did not have data on the reason for hospital admission among patients in the Hospitalized group, nor did we have the referral source (i.e., referral from the hospital vs the outpatient area). This potentially could have biased the results, because patients already living at home who are starting up home care services may not be as acutely ill as patients recently discharged from the hospital. Although we tried to recognize this limitation by using diagnostic categories that were more detailed than in previous studies on health care utilization ^(9)(10), severity of illness was not measured beyond that. Nonetheless, if clinicians are looking for indices for severity of illness or predictors of hospitalization, a higher number of medications should still be on their list.

In conclusion, the main finding of this study is that for this group of older home care patients, the Hospitalized group compared with the S/F Care group had a higher degree of polypharmacy defined by cutoff points of 7 or more and 10 or more medications. Whether a higher number of medications is an indicator of sicker patients at risk for hospitalization, or a higher number of medications might directly lead to hospitalization, the clinical implication is that polypharmacy should be considered a marker for older home care patients at risk for hospitalization. If one of the goals of home care is to prevent hospitalization, then the clinical implications of this study are to develop interventions directed at patients with polypharmacy to see if hospitalization rates can be reduced. The type of interventions (e.g. reducing number of medications, or increasing home care services to patients with polypharmacy) that work best, remains to be seen.

	Acknowledgments

Received July 1, 1999

Accepted March 29, 2000

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