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Background: Prescription claims data have been used to estimate refill medication adherence through calculations of cumulative medication acquisition (CMA) and cumulative medication gap (CMG) values. Few studies have assessed the validity of these calculated rates., Objectives: We sought to assess the validity of CMA and CMG calculated from the Manitoba prescription claims database (DPIN) against pill count medication adherence, targeting overall medications and angiotensin converting enzyme inhibitors (ACEIs)., Methods: Using a survey of a convenience sample of subjects recruited through community pharmacies, subjects who were eligible for study (ie, 65 years or older, noninstitutionalized, taking 2 or more "discrete" prescribed medications, including an ACEI, and willing to provide informed consent) were studied. Pill counts were conducted on all prescribed medicines during 3 home interviews over the course of 4 months. Ten months of DPIN data also were collected on each subject., Results: The concordance between CMA and pill count for overall medications was 411/522 (79%) and for ACEIs was 89/101 (88%) with no systematic differences (McNemar's P = 0.68 and P = 0.097, respectively). CMG and pill count showed even better concordance of 438/514 (85%) for overall medications and 96/101 (95%) for ACEIs, although systematic differences were noted for overall medications (McNemar's P = 0.0012) but not for ACEIs (McNemar's P = 0.500). Spearman's rank correlations were weak for all comparisons., Conclusions: The high concordance between prescription claims database and pill counts suggested that the rate with which patients refill their medications usually is consistent with the rate they consume them. DPIN is not accurate for nondiscrete dosage forms or medications prescribed for "as-required" use.

Objective: To compare medication adherence calculated from four different data sources including a pill count and self-report obtained during a home medication history, as well as calculations based on refill frequency derived from a provincial prescription claims database (manual and electronic)., Design: Baseline medication adherence was collected as part of a prospective, randomized, controlled study. Mean medication adherence results obtained from the four data sources were compared using repeated-measures ANOVA followed by a Tukey's multiple range test., Setting: A pharmacy consultation service located at an interdisciplinary wellness center for noninstitutionalized elderly., Patients: 65 years or older, noninstitutionalized, taking one or more prescribed or nonprescribed medications. Clients would either present to the wellness center or be referred by the Provincial Home Care program., Results: When calculated from self-report or manual or electronic prescription claims data, mean percent adherence by drug was high and not statistically different (95.8% +/- 17.1%, 107.6% +/- 40.3%, and 94.6% +/- 24.0%, respectively), whereas the pill count adherence was significantly lower at 74.0% +/- 41.5% (p < 0.0001)., Conclusions: An unexpected finding was that the pill count technique used in this study of elderly clients using chronic, repeat medications appeared to underestimate medication adherence. Numerous other limitations of pill count, self-report, and a province-wide prescription claims database in estimating medication adherence are presented. When using medication adherence as a process measure, the researcher and practitioner should be aware of the limitations unique to the data source they choose, and interpret data cautiously.

Patterns of drugs prescribed for elderly community-dwelling heavy medicinal drug users were determined from random samples of data bases and compared between Manitoba, Canada and Jämtland, Sweden for the year 1981. Qualitatively, there was 80% concordance between the 20 most frequently prescribed drugs in Manitoba and in Jämtland. Gender differences were rare, but there were notable quantitative differences for prescription of specific drugs between the two jurisdictions. Drugs to treat cardiovascular diseases were prominent in both groups with thiazides, triamterene and alpha-methyldopa more frequently prescribed for Manitoba patients, and furosemide, potassium supplements and digoxin more frequently prescribed for patients from Jämtland. The frequent prescribing of codeine in combination analgesics in Manitoba and phenothiazines in Jämtland appears to represent geographically disparate approaches to the use of these drugs. Overall, the concordance of prescribed drugs for elderly heavy medicinal drug users from these two jurisdictions appears to outweigh the differences. These results indicate that data from studies of heavy medicinal drug users, at least in the industrialized world, may be more widely applicable than to the geographical location from where they were obtained.

We report an analysis of prescription drugs claimed under a government-sponsored, universal Pharmacare program for community-dwelling adults aged greater than or equal to 50 years in Manitoba during 1975, 1978, 1981, and 1984. We limited our analysis to claimants who reported over six drugs in a year in order to control for effects of inflation and a changing deductible. The median number of prescribed drugs and the percent of claimants over age 50 years receiving prescriptions from multiple physicians decreased during the course of our study. In this sample of heavy drug users, age and sex did not consistently correlate with overall drug use, although there was correlation for specific drug groups. The relative ranking of prescribed drugs changed over the years, although benzodiazepines, thiazide diuretics, topical steroids, and codeine-containing analgesics remained near the top. Barbiturates and topical antibiotics showed the greatest drop in prescription rates; acetaminophen and beta-blockers increased the most. Using these community data, we project the prevalence of drug-related adverse events to be highest with beta-blockers, nonsteroidal antiinflammatory drugs, thiazide diuretics, and benzodiazepines.

A survey of drug-related admissions of patients aged 50 years and older was conducted at the Health Sciences Centre, Winnipeg to determine the interrelationship of risk factors, and isolate the effect of age. All nonelective medical admissions were prospectively assessed to determine the role of drug therapy as a contributory factor. Of the 863 eligible admissions, 162 exhibited at least one drug-related adverse patient event (DRAPE) at the time of hospitalization. This accounted for 19% of the admissions (23% of 718 admissions that involved prescription drugs). Although adverse drug reactions were responsible for many DRAPEs (48%), intentional noncompliance (27%), treatment failure (19%), alcohol (14%), and medication error (10%) were also frequent contributing causes. Drugs commonly implicated in DRAPEs were systemic steroids, digoxin, nonsteroidal anti-inflammatory agents, alpha-methyldopa, calcium channel blockers, beta-blockers, theophylline, furosemide, sympathomimetics, thiazides, and benzodiazepines. The risk of a DRAPE was related to the number of diseases prior to admission (r = 0.81; P less than .026) and the number of drugs used (r = 0.77; P less than .001). Age was not correlated with the risk of a DRAPE. Females had significantly more adverse drug reactions, although sex was not a predictor for overall DRAPE risk.

A random sample of claimants under Manitoba's Pharmacare plan provided information on the drugs prescribed for those individuals who spent more than $50 for drugs in 1978. More women than men were represented among the 412 claimants aged 50 to 64 (58% females), and more drugs were prescribed for women than men (8.38 +/- 3.4 vs. 7.17 +/- .33, mean +/- S.E.M., p less than 0.02). For the 403 claimants aged 65 and older, the sex distribution matched that of the general population (55%), and the difference in number of drugs prescribed was not statistically significant (8.49 +/- .36 vs 7.98 +/- .35). For the claimants aged 65 and older, the five most heavily prescribed drug categories were thiazide-type diuretics (prescribed for 51.6% of older claimants in 1978), benzodiazepines (40.0%), salicylates (26.8%), digoxin (22.6%) and codeine (20.8%). There were few differences in prescription frequencies between younger and older claimants, and these data indicate that drugs prescribed for heavy drug users do not change markedly as a function of age.