OBJECTIVES To examine the prevalence of potentially inappropriate medication use (PIMs) among community-dwelling older adults in a managed care organization (MCO) and the association between PIMs and selected health care outcomes.

DESIGN, MEASURES, ANALYSIS•Retrospective cohort study.

•Participants were 17,971 individuals in the southeast age 65 years and older who were continuously enrolled for a 6-month period from January 1-June 30, 2000.

•PIM use was defined by the Beers criteria; any subject using at least one such drug was defined to be in the PIM group.

•ICD-9 codes for medical diagnoses were taken from the discharge diagnosis.

•Comorbidity was measured using the Deyo-adapted Charlson index.

•Drug-related problems (DRPS) were defined using ICD-9 codes for principal and secondary diagnoses occurring within 30 days after a drug was started.

•Health care costs, were based on MCO claims data.

Donna Fick, PhD, RN1; Lorraine C. Mion, PhD, RN, FAAN2; Diane Spokus, M.Ed1

1The Pennsylvania State University, University Park, PA; 2MetroHealth Campus of Case Western Reserve University School of Medicine, Cleveland, Ohio

METHODS

Health Outcomes Associated With Potentially Inappropriate Medication Use In Older Adults

Adverse drug events (ADEs) are prevalent in the older adult population and pose a major patient safety concern. ADEs arise because of the increasing number of medications required by this age group, pre-existing health conditions, and the pharmacokinetic and pharmacodynamic changes that occur with aging.1, 2 Avoiding use of high-risk drugs is an important strategy in reducing ADEs.

INTRODUCTION Table 1. Characteristics of the Study Sample, Medication Use and Overall Cost

Forty percent of the 17,971 individuals filled at least 1 PIM prescription, and 13% filled 2 or more PIMs prescriptions. Overall DRP prevalence, among those with at least 1 PIM prescription was 14.3% compared to 4.7% in the non-PIM group (p<0.0001). Those individuals taking 2 or more PIMs had the highest cost and utilization (F=522.2, p<0.0001).

IMPLICATIONSThese findings should be used to create interventions to decrease the use of PIMS now that we have established the adverse clinical and cost outcomes of their collective use. This study also illustrates the need to study which drugs listed in the Beers criteria cause the most problems. This will require a larger prospective study.

ACKNOWLEDGEMENTS

Blue Cross Blue Shield of Georgia for data acquisition and data support. Shari Walczak for dissemination expertise.

Use of even one PIM by elderly patients increases the likelihood of drug-related problems by nearly 3 fold within 30 days and increases healthcare utilization and costs over 6 months.

Overall Costs for PIM and non-PIM Group

$0.00$500.00

$1,000.00$1,500.00$2,000.00$2,500.00

PIMS* (N-6,875)Mean

Comparisons (N=10,002) Mean

RESULTS

Given the retrospective nature of the study, our measures for drug-related problems are limited in their ability to infer causality and will require further testing in a prospective study. The other limitations of this study are similar to that of other studies that use administrative data: problems with coding, changing reimbursements, high patient turnover, and the limits of the available economic and clinical data.

Table 2. Distribution of Each Potentially Inappropriate Medication (N=17,971)*

Inappropriate Medication N Percent

Estrogens only 1718 9.56

Propoxyphene and combination products 1333 7.42

Doses of short acting benzodiazepines 1327 7.38

Digoxin 846 4.71

Long-term use of full dosage longer half-life 832 4.63

non-Cox selective NSAIDS agents

Anticholinergics and antihistamines 689 3.83

Muscle relaxants and antispasmodics 577 3.21

Doxazosin 427 2.38

Amitriptyline (Elavil, Limbitrol, or Triavil) 407 2.26

Macrodantin 229 1.27

Long-acting benzodiazepines 329 1.83

Clonidine 274 1.52

Short-acting nifedipine 239 1.33

Gastrointestinal antispasmotics 245 1.36

Daily fluoxetine 216 1.20

Indomethacin 139 0.77

Cimetidine 103 0.57

Ketorolac 97 0.54

Barbiturates 95 0.53

Amiodarone 77 0.43

Doxepin 88 0.49

Desiccated thyroid 30 0.17

Short-acting dipyridamole 46 0.26

Methyldopa 28 0.16

Flurazepam (Dalmane) 27 0.15

Ticlopidine 27 0.15

Orphenadrine 22 0.12

Meperidine 19 0.11

Trimethobenzamide (Tigan) 14 0.08

Thioridazine 14 0.08

Meprobamate 12 0.07

Disopyramide (Norpace) 10 0.06

Reserpine at doses >0.25mg 12 0.07

Pentazocine (Talwin) 5 0.03

Ferrous sulfate >325mg Daily 3 0.02

Chlorpropamide (Diabenese) 2 0.01

Ethacrynic acid 1 0.01

Isoxsuprine 1 0.01

Methyltestosterone 1 0.01

* As defined by the updated Beers criteria (Fick et al, 2003)

Inappropriate

Medication Types N Percent

0 10694

59.51

1 4862 27.05

2 1682 9.36

3 549 3.05

4 134 0.75

5 39 0.22

6+ 11 0.06

As defined by the updated Beers criteria (Fick et al, 2003)

LIMITATIONS

Table 4. Chi-square or Fisher’s Exact Tests between Individuals with PIMS & Comparison Individuals for Prevalence of Drug-related Problems (DRP) within 30 Days of a Prescription

Table 2. Distribution of Each Potentially Inappropriate Medication (N=17,971)*

PIMS

Comparisons

(N=6875) (N=10002) Odds

Variable N % N % Ratio 95% CI x2 P value

Alteration of consciousness 35 0.51 14 0.14 3.65 1.96 – 6.79 19.18 <0.0001

Syncope 246 3.58 122 1.22 3.01 2.41 – 3.74 106.25 <0.0001

Sleep disturbances 102 1.48 42 0.42 3.57 2.49 – 5.12 54.50 <0.0001

Malaise and fatigue 237 3.45 106 1.06 3.33 2.65 – 4.20 116.64 <0.0001

Retention of urine 52 0.76 26 0.26 2.92 1.82 – 4.69 21.83 <0.0001

Urinary incontinence 61 0.89 24 0.24 3.72 2.32 – 5.97 34.07 <0.0001

Adverse effect 21 0.31 12 0.12 2.55 1.25 – 5.19 7.18 0.0074

Bradycardia 50 0.73 25 0.25 2.92 1.81 – 4.72 20.98 <0.0001

Dehydration 126 1.83 44 0.44 4.23 2.99 – 5.96 79.27 <0.0001

Acute depression 16 0.23 3 0.03 7.77 2.26 – 26.69 14.89 0.0001

Falls 25 0.36 9 0.09 4.05 1.89 – 8.69 15.18 <0.0001

Hemorrhage bowel 49 0.71 18 0.18 3.98 2.32 – 6.84 29.25 <0.0001

Gastritis 17 0.25 8 0.08 3.10 1.34 – 7.18 7.71 0.0055

Hypoglycemia 15 0.22 13 0.13 1.68 0.80 – 3.53 1.91 0.1665

Hypotension 20 0.29 8 0.08 3.64 1.60 – 8.28 10.94 0.0009

Hip fracture 34 0.49 16 0.16 3.10 1.71 – 5.62 15.44 <0.0001

Femur fracture 14 0.20 3 0.03 6.80 1.95 – 23.67 12.21 0.0001

Confusion 17 0.25 11 0.11 2.25 1.05 - 4.81 4.64 0.0313

Dementia 61 0.89 28 0.28 3.18 2.04 – 4.99 28.65 <0.0001

Delirium 32 0.47 14 0.14 3.34 1.78 – 6.26 15.88 <0.0001

Any cognitive impairment 100 1.45 51 0.51 2.88 2.05 – 4.04 41.00 <0.0001

Any proxy DRP 981 14.27 468 4.68 3.39 3.02 – 3.80 477.44 <0.0001

PIMS* Comparisons

(N-6,875) (N=10,002) t-test

Mean SD Mean SD or x2 P value

Female sex (n, %) 4882 71.01 5436 54.36 476.06 <0.0001

Age 73.48 6.53 73.23 6.45 -2.47 0.0136

Co-morbidity index 0.84 1.38 0.60 1.08 -12.00 <0.0001

Total paid costs $2257.37 6260.54 $1119.51 5080.77 -12.50 <0.0001

Facility paid costs $1663.60 5610.45 $783.40 4659.33 -10.71 <0.0001

Provider paid costs $401.17 1082.57 $221.04 1083.73 -10.61 <0.0001

Prescription costs $192.59 186.39 $115.07 151.79 -28.58 <0.0001

Inpatient visits 0.18 0.61 0.08 0.37 -12.67 <0.0001

Outpatient visits 0.88 1.38 0.53 0.99 -18.26 <0.0001

Office visits 6.55 6.55 4.45 4.77 -22.73 <0.0001

ER visits 0.17 0.49 0.08 0.31 -13.41 <0.0001

Total prescriptions 14.55 9.77 6.18 6.53 -62.15 <0.0001

(including refills)

Total prescription types 6.26 3.58 2.76 2.56 -69.65 <0.0001

Total PIMS 3.71 2.99

(including refills)

Total unique PIM types 1.48 0.79

* PIMS = potentially inappropriate medications

Table 3. Number of Inappropriate Medications Types