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Purpose: To review the literature describing patterns of outpatient prescription drug use during pregnancy by therapeutic category, potential for fetal harm, and overall., Methods: We conducted a systematic review of peer-reviewed literature published from 1989 to 2010. We included studies evaluating individual-level exposures to prescription medicines during pregnancy. We selected only studies conducted in developed (Organization of Economic Co-operation and Development) countries and published in English., Results: Published drug utilization studies reveal wide variation in estimates of overall prescription drug use in pregnancy (27-93% of pregnant women filling at least one prescription excluding vitamins and minerals). Among studies of similar design, estimates were lowest in Northern European countries (44-47%) and highest in France (93%) and Germany (85%). Measured rates of use of contraindicated medicines in pregnancy ranged from 0.9% (Denmark, 1991-1996) to 4.6% (USA, 1996-2000). The use of medicines with positive evidence of risk ranged from 2.0% (Italy, 2004) to 59.3% (France, 1996)., Conclusion: Avoidable inconsistencies in study design and reporting attenuate conclusions that can be drawn from the literature on antenatal drug utilization. Nevertheless, the body of published research shows that antenatal prescription drug use is common, with many studies finding that a majority of women use one or more prescription medicine during pregnancy. Similarly, studies consistently report the use of drugs recognized as having potential risks in pregnancy. Given this widespread use, it is particularly important to develop standards for calculating and reporting antenatal exposures to improve the value of future research in this area., (Copyright © 2011 John Wiley & Sons, Ltd.)

Canada's provincial and territorial governments have expressed an interest in bulk purchasing prescription drugs for many years. We propose they start by purchasing selected generic drugs for the entire population and provide them for little or no cost to patients. This politically popular strategy would significantly reduce drug expenditures and improve population health.

Background: This study aimed to measure the income-related inequalities and inequities - the inequalities that remain after accounting for differences in health need - in expenditure on fully publicly covered (hospital and ambulatory) and partially publicly covered (prescription drugs) services for those in their last year of life in the province of British Columbia (B.C.), Canada. We focused on a decedent population for three reasons: to minimize unmeasured need differences among our cohort and therefore isolate income effects; to explore inequities for a high-spending window of health care use; and, because previous studies have found conflicting relationships between income and decedent health care spending, to further quantify this relationship., Methods: We used linked administrative databases to describe spending on health services by income for all 58,820 deaths of B.C. residents 65 and older from 2004 to 2006. Regression analyses examined the association between income and health care spending, adjusting for age, sex, health status, cause of death, and other relevant factors. We then used concentration indexes to measure both inequalities and inequities separately for three key types of services. Analyses were also run separately for men and women., Results: On average, per capita expenditure on acute health care in the last year of life was $20,705 (CDN2006). In need-adjusted regression analyses, we found decedents in the highest income quintile had 11% lower hospital expenditures, 15% higher specialist expenditures and 23% higher prescription drug expenditures than decedents in the lowest income quintile. Concentration index analysis suggested that spending for all types of care was concentrated among those with higher income before adjusting for need. Need-adjusted equity results mirrored regression findings and suggested patterns of inequities that were more pronounced among male decedents than females., Conclusions: Despite the universal health care system in B.C., we found patterns of inequity in spending by income in the last year of life, even for fully publicly covered services. These results, parallel to relationships between income and spending from previous studies of the B.C. population, suggest persistent income-related inequities in the health care Canadians receive throughout their lives.

Background: The Internet has become a popular source of health information. However, there is little information on what drug information and which Web sites are being searched., Objective: To investigate the sources of online information about prescription drugs by assessing the most common Web sites returned in online drug searches and to assess the comparative popularity of Web pages for particular drugs., Methods: This was a cross-sectional study of search results for the most commonly dispensed drugs in the US (n=278 active ingredients) on 4 popular search engines: Bing, Google (both US and Canada), and Yahoo. We determined the number of times a Web site appeared as the first result. A linked retrospective analysis counted Wikipedia page hits for each of these drugs in 2008 and 2009., Results: About three quarters of the first result on Google USA for both brand and generic names linked to the National Library of Medicine. In contrast, Wikipedia was the first result for approximately 80% of generic name searches on the other 3 sites. On these other sites, over two thirds of brand name searches led to industry-sponsored sites. The Wikipedia pages with the highest number of hits were mainly for opiates, benzodiazepines, antibiotics, and antidepressants., Conclusions: Wikipedia and the National Library of Medicine rank highly in online drug searches. Further, our results suggest that patients most often seek information on drugs with the potential for dependence, for stigmatized conditions, that have received media attention, and for episodic treatments. Quality improvement efforts should focus on these drugs.

Background: Proximity is an important component of access to healthcare services. Recent changes in generic pricing in Ontario have caused speculation about pharmacy closures. However, there is little information on the current geographic accessibility of pharmacies. Therefore, we studied geographic access to pharmacies and modelled the impact of possible closures., Methods: We used location data on the 3,352 accredited community pharmacies from the Ontario College of Pharmacists and population estimates at the census dissemination block level. Using network analysis, we determined the share of Ontario's population who reside in a census dissemination block within three road travel distances of a community pharmacy: 800 m (walking), 2 km and 5 km (driving). We then simulated the effects on these measures of 10% to 50% reductions in the number of community pharmacies in Ontario., Results: Approximately 63.6% of the Ontario population reside in a dissemination block located within walking distance of one or more pharmacies; 84.6% and 90.7% reside within 2-km and 5-km driving distances, respectively. Randomly removing 30% of Ontario's community pharmacies reduces these estimates to 56.0%, 81.4% and 89.0% for each distance, respectively; a 50% reduction results in 48.3%, 77.1% and 87.2%, respectively., Conclusions: Pharmacies are geographically accessible for a majority of the Ontario population. Moreover, it appears that modest closures would have only a small impact on geographic access to pharmacies. However, closures may have other impacts on access, such as cost, waiting time and reduced patient choice.

Background: Canadians pay amongst the highest generic drug prices in the world. In July 2010, the province of Ontario enacted a policy that halved reimbursement for generic drugs from the public drug plan, and substantially lowered prices for private purchases. We quantified the impact of this policy on overall generic drug expenditures in the province, and projected the impact in other provinces had they mimicked this pricing change., Methods: We used quarterly prescription generic drug dispensing data from the IMS-Brogan CompuScript Audit. We used the price per unit in both the pre- and post-policy period and two economics price indexes to estimate the expenditure reduction in Ontario. Further, we used the post-policy Ontario prices to estimate the potential reduction in other provinces., Results: We estimate that total expenditure on generic drugs in Ontario during the second half of 2010 was between $181 and $194 million below what would be expected if prices had remained at pre-policy level. Over half of the reduction in spending was due to savings on just 10 generic ingredients. If other provinces had matched Ontario's prices, their expenditures over during the latter half of 2010 would have been $445 million lower., Discussion: We found that if Ontario's pricing scheme were adopted nationally, overall spending on generic drugs in Canada would drop at least $1.28 billion annually--a 5% decrease in total prescription drug expenditure. Other provinces should seriously consider both changes to their generic drug prices and the use of more competitive bulk purchasing policies.

Background: Increasing attention is being paid to variations in the use of prescription drugs because their role in health care has grown to the point where their use can be considered a proxy for health system performance. Studies have shown that prescription drug use varies across regions in the US, UK, and Canada by more than would be predicted based on age and health status alone. In this paper, we explore the determinants of variations in the use of prescription drugs, drawing on health services theories of access to care., Methods: We conducted a cross-sectional analysis using population-based administrative health care data for British Columbia (BC), Canada. We used logistic and hierarchical regressions to analyze the effects of individual- and area-level determinants of use of prescriptions overall and rates of purchase of prescriptions from five therapeutic categories representing a range of indications: antihypertensives, statins, acid reducing drugs, opioid drugs, and antidepressants. To indicate the relative scale of regional variations and the importance of individual- and area-level variables in explaining them, we computed standardized rates of utilization for 49 local health areas in BC., Results: We found that characteristics of individuals and the areas in which they live affect likelihood of prescription drug purchase. Individual-level factors influenced prescription drug purchases in ways generally consistent with behavioral models of health services use. Contextual variables exerted influences that differed by type of drug studied. Population health, education levels, and ethnic composition of local areas were associated with significant differences in the likelihood of purchasing medications. Relatively modest regional variations remained after both individual-level and area-level determinants were taken into account., Conclusions: The results of this study suggest that individual- and area-level factors should be considered when studying variations in the use of prescription drugs. Some sources of such variations, including individual- and area-level socioeconomic status, warrant further investigation and possible intervention to address inequities.

Background: Sex and gender sensitive inquiry is critical in pharmaceutical policy due to the sector's historical connection with women's health issues and due to the confluence of biological, social, political, and economic factors that shape the development, promotion, use, and effects of medicinal treatments. A growing number of research bodies internationally have issued laws, guidance or encouragement to support conducting sex and gender based analysis (SGBA) in all health related research., Methods: In order to investigate the degree to which attempts to mainstream SGBA have translated into actual research practices in the field of pharmaceutical policy, we employed methods of literature scoping and mapping. A random sample of English-language pharmaceutical policy research articles published in 2008 and indexed in MEDLINE was analysed according to: 1) use of sex and gender related language, 2) application of sex and gender related concepts, and 3) level of SGBA employed., Results: Two thirds of the articles (67%) in our sample made no mention of sex or gender. Similarly, 69% did not contain any sex or gender related content whatsoever. Of those that did contain some sex or gender content, the majority focused on sex. Only 2 of the 85 pharmaceutical policy articles reviewed for this study were primarily focused on sex or gender issues; both of these were review articles. Eighty-one percent of the articles in our study contained no SGBA, functioning instead at a sex-blind or gender-neutral level, even though the majority of these (86%) were focused on topics with sex or gender aspects., Conclusions: Despite pharmaceutical policy's long entwinement with issues of sex and gender, and the emergence of international guidelines for the inclusion of SGBA in health research, the community of pharmaceutical policy researchers has not internalized, or "mainstreamed," the practice. Increased application of SGBA is, in most cases, not only appropriate for the topics under investigation, but well within the reach of today's pharmaceutical policy researchers.

Background: Granting dispensing pharmacists the authority to prescribe has significant implications for pharmaceutical and health human resources policy, and quality of care. Despite the growing number of jurisdictions that have given pharmacists such privileges, there are few rigorous evaluations of these policy changes. This study will examine a January 2009 policy change in British Columbia (BC), Canada that allowed pharmacists to independently adapt and renew prescriptions. We hypothesize this policy increased drug utilization and drug costs, increased patient adherence to medication, and reduced total healthcare resource use., Methods/design: We will study a population-based cohort of approximately 4 million BC residents from 2004 through 2010. We will use data from BC PharmaNet on all of the prescriptions obtained by this cohort during the study period, and link it to administrative billings from physicians and hospital discharges. Using interrupted time series analysis, we will study longitudinal changes in drug utilization and costs, medication adherence, and short-term health care use. Further, using hierarchical modelling, we will examine the factors at the regional, pharmacy, patient, and prescription levels that are associated with prescription adaptations and renewals., Discussion: In a recent survey of Canadian policymakers, many respondents ranked the issue of prescribing privileges as one of their most pressing policy questions. No matter the results of our study, they will be important for policymakers, as our data will make policy decisions surrounding pharmacist prescribing more evidence-based.

The ability of miniscule larvae to control their fate and replenish populations in dynamic marine environments has been a long-running topic of debate of central importance for managing resources and understanding the ecology and evolution of life in the sea. Larvae are considered to be highly susceptible to offshore transport in productive upwelling regions, thereby increasing dispersal, limiting onshore recruitment, and reducing the intensity of community interactions. We show that 45 species of nearshore crustaceans were not transported far offshore in a recruitment-limited region characterized by strong upwelling. To the contrary, 92% of these larvae remained within 6 km from shore in high densities throughout development along two transects sampled four times during the peak upwelling season. Larvae of most species remained nearshore by remaining below a shallow Ekman layer of seaward-flowing surface waters throughout development. Larvae of other species migrated farther offshore by occurring closer to the surface early in development. Postlarvae evidently returned to nearshore adult habitats either by descending to shoreward-flowing upwelled waters or rising to the sea surface where they can be transported shoreward by wind relaxation events or internal waves. Thus wind-driven offshore transport should not limit recruitment, even in strong upwelling regions, and larvae are more likely to recruit closer to natal populations than is widely believed. This study poses a new challenge to determine the true cause and extent of recruitment limitation for a more diverse array of species along upwelling coasts, and thus to further advance our understanding of the connectivity, dynamics, and structure of coastal populations.

The ability of microscopic larvae to control their fate and replenish populations in dynamic marine environments has been a long-running topic of debate of central importance to understanding the ecology and evolution of life in the sea and managing resources in a changing global environment. After decades of research documenting behaviors that keep larvae close to natal populations, it is becoming apparent that larval behaviors in a broader spectrum of species promote long-distance migrations to offshore nursery grounds. Larvae must exert considerable control over their movements. We now show that larval emigration from estuaries is favored even over minimizing visibility to predators. An endogenous tidal vertical migration that would expedite seaward migration of Uca pugilator larvae was maintained experimentally across two tidal regimes. The periodicity of the rhythm doubled to match the local tidal regime, but larvae ascended to the surface during the daytime rather than at night. This process would conserve larval emigration but increase the visibility to predators across part of the species range. The periodicity of tidal vertical migration by Sesarma cinereum larvae failed to double and was inappropriately timed relative to both environmental cycles in the absence of a diel cycle. The timing system regulating tidally timed behaviors in these two species of crabs evidently differed. Phenotypic plasticity can conserve larval transport of both species when tidal and diel cycles are present. It may be widespread in the sea where diverse habitats are encountered across extensive species ranges.

Objective: The purpose of this research was to measure prevalent and incident statin use in the population of British Columbia from 1996 to 2004 across specific patient characteristics (sociodemographic and clinical)., Methods: Statin utilization and demographic data were assessed with the use of prescription drug claims. Medical and hospital claims for statin users were examined for evidence of ischemic heart disease (IHD), diabetes mellitus (DM), atherosclerosis, cerebrovascular disease, peripheral vascular disease (PVD), and disorders of lipid metabolism during the 3 years before the first statin prescription., Results: Statin prevalence increased from 1996 to 2004 (1.28 %-6.59%). The greatest use was among those aged 65 to 84 years. Prevalent use of atorvastatin, simvastatin, and rosuvastatin increased over time. There were 211,964 new statin users between 1999 and 2004. Quarterly incident statin use increased over time from 1999 to 2004 (0.29%-0.49%). A socioeconomic gradient, whereby use was greater in those with low socioeconomic status, was observed for incident statin use. Incident atorvastatin use increased over time; simvastatin, cerivastatin, and rosuvastatin peaked and then declined; and new use of other statins decreased. Among 211,964 incident statin users, 74,542 (35.17%) had evidence of IHD only; 43,257 (20.41%) had DM but no IHD; 9781 (4.61%) had no DM or IHD but had atherosclerosis, cerebrovascular disease, or PVD; 47,634 (22.47%) had disorders of lipid metabolism only; and 36,750 (17.34%) had none of the medical conditions evaluated., Conclusions: Prevalent use (1996-2004) and incident use (1999-2004) of statins in an entire population have increased dramatically. Although many statin users (60.19%) had evidence of medical conditions that indicate appropriate statin use, 39.91% of users were at low risk for cardiovascular disease, and therefore the benefit of statins in this group remains small.

Background: Long-term utilization of prescription drugs for chronic conditions such as hypertension and/or hypercholesterolemia is a reality for millions of individuals, yet therapies may be discontinued before they can exert their beneficial effect. Several studies have measured the mean duration of therapy (ie, persistence) using administrative health databases. However, the terminology and methodology used for measuring persistence varied across studies, making it difficult to compare persistence rates., Objectives: The objectives of this study were to identify currently used measures of persistence and to propose a standard operational definition for use in administrative database analyses of drug utilization., Methods: MEDLINE was searched for English-language articles published between January 1997 and June 2005 that quantified the concepts of persistence, adherence, compliance, or continuity with statin or antihypertensive therapy using administrative prescription claims databases. The conceptual and operational definitions of persistence used in the identified studies were categorized and applied to prescription-refill data for a hypothetical patient to compare the durations of persistence resulting from each method., Results: Thirty-one articles were identified and reviewed. Few of the studies explicitly stated the conceptual definition of persistence used. Five methods of measuring persistence were identified: anniversary models, minimum-refills models, refill-sequence models, proportion-of-days-covered models, and hybrid models. When these models were applied to data for the hypothetical patient, total persistence with drug therapy ranged from 7 days to >1 year., Conclusions: There continue to be inconsistencies in the definition of persistence and the methods by which it is measured. A standard operational definition of persistence should be 2-dimensional, quantifying not only the total duration of therapy, but also the intensity of medication-taking within this interval.

A challenge in environmental management is to provide both methodology and a framework for assessing effects of pollutants in resident species and then applying the findings to management. The Pacific Estuarine Ecosystem Indicator Research (PEEIR) consortium advocates the development of an integrated portfolio of techniques using indicator species selected for various habitat types. We developed such a portfolio for California salt marsh ecosystems and evaluated the feasibility of our approach in management applications. PEEIR is employing a suite of biomarker responses in two indigenous species, the lined shore crab (Pachygrapsus crassipes) and the longjaw mudsucker (Gillichthys mirabilis). Detrimental effects such as apoptosis, endocrine disruption, and ovarian tumors have been observed in G. mirabilis at a site where toxicity test responses were relatively low. With P. crassipes, developmental abnormalities and several markers of decreased reproductive performance were quantified at the same site. Multivariate statistical techniques are used to examine the relationships between the responses and multiple contaminant and natural stressors. For the fish, findings are related to population-level parameters using dynamic energy budget (DEB) models.

Objective: To provide detailed demographic profiles of prescription drug utilization and expenditures in order to isolate the impact of demographic change from other factors that affect drug expenditure trends., Data Sources/study Setting: Demographic information and drug utilization data were extracted for virtually the entire British Columbia (BC) population of 1996 and 2002. All residents had public medical and hospital insurance; however their drug coverage resembled the mix of private and public insurance in the United States., Study Design: A series of research variables were constructed to illustrate profiles of drug expenditures and drug utilization across 96 age/sex strata., Data Collection/extraction Methods: Drug use and expenditure information was extracted from the BC PharmaNet, a computer network connecting all pharmacies in the province., Principal Findings: Per capita drug expenditures increased at an average annual rate of 10.8 percent between 1996 and 2002. Population aging explained 1.0 points of this annual rate of expenditure growth; the balance was attributable to rising age/sex-specific drug expenditures., Conclusions: Relatively little of the observed increase in drug expenditures in BC could be attributed to demographic change. Most of the expenditure increase stemmed from the age/sex-specific quantity and type of drugs purchased. The sustainability of drug spending therefore depends not on outside forces but on decisions made by policy makers, prescribers, and patients.

Phenotypic plasticity is widespread in nature, and often involves ecologically relevant behavioral, physiological, morphological and life-historical traits. As a result, plasticity alters numerous interactions between organisms and their abiotic and biotic environments. Although much work on plasticity has focused on its patterns of expression and evolution, researchers are increasingly interested in understanding how plasticity can affect ecological patterns and processes at various levels. Here, we highlight an expanding body of work that examines how plasticity can affect all levels of ecological organization through effects on demographic parameters, direct and indirect species interactions, such as competition, predation, and coexistence, and ultimately carbon and nutrient cycles.

Background: Prescription drug expenditures in North America have nearly doubled in the past 5 years, creating intense pressure for all public and private benefits managers and policymakers., Objective: The objective of this study was to describe age-specific drug expenditure trends from 1996 to 2002 for the Canadian province of British Columbia., Study Design: This study shows changes in expenditures per capita quantified for 5 age categories: residents aged 0 to 19, 20 to 44, 45 to 64, 65 to 84, and 85 and older. The cost impacts of 7 determinants of prescription drug expenditures are quantified., Data: This study describes population-based, patient-specific pharmaceutical data showing the type, quantity, and cost of every prescription drug purchased by virtually all residents of British Columbia., Results: Population-wide expenditures per capita grew at a rate of 11.6% per annum. Growth was primarily driven by the selection of more costly drugs per course of treatment and increases in the number concomitant treatments received per patient. Population aging did not have a major impact on expenditures. However, expenditure per capita grew most rapid among residents aged 45 to 64, the cohort that expended most over the period. The aging of this demographic cohort may threaten the financial viability of age-based drug benefit programs.

Background: Previous research has documented low levels of persistence with prescribed hypertension treatment in Canada. With growing recognition of the value of appropriate drug therapy, rates of persistence may be improving over time. The purpose of this study was to examine persistence with prescribed hypertension treatment among newly treated community-dwelling seniors in British Columbia., Methods: BC PharmaCare data was used to determine the cohort of seniors who were newly-treated hypertensives over the period 1993 to 2000. Medical and hospital claims from the BCLHD were searched for diagnoses indicating the presence of essential hypertension and potentially confounding conditions. Rates of persistence with drug therapy were analysed, accounting for patient, age, sex, clinical complexity, the existence of potentially confounding conditions, and type of drug first prescribed., Results: For the period 1993 to 2000, 82,824 seniors were identified as new users of hypertension drugs with diagnosed essential hypertension. Fifty-one percent of these newly-treated hypertensives filled a contiguous series of hypertension prescriptions for at least one full year. There was a slight improvement in the rate of persistence over time (p<0.001). Evidence of specific co-morbidities that potentially complicate essential hypertension increased the likelihood of persistence among first-time users (p<0.001), whereas greater overall clinical complexity decreased the likelihood of persistence (p<0.001). Persistence was highest amongst patients initiated on newer anti-hypertensive drug therapies., Conclusions: Despite modest improvement, persistence with hypertension treatment among the elderly is very low. Further research into the reasons for non-persistence would be advanced through primary data collection, including survey-based research. New policies and practices are needed to encourage persistence with evidence-based therapies.

We develop an analytic framework to map out the nature and relative importance of different cost-driving trends in the prescription drug market. This is used to measure prescription drug cost-drivers for the population of seniors in British Columbia during a period when they received comprehensive public drug coverage. Between 1991 and 2001, expenditures on prescription drugs for BC seniors increased from dollar 149 to 320 million. Increases in the population of seniors, and the rate at which they utilized therapies contributed under half of the total cost increase over the period. Changes in the mix of therapies and the type of product selected explained over half of the observed drug expenditure inflation. Increased generic substitution significantly reduced the price of products selected over the period.

Canada's public-private mix in coverage for pharmaceuticals has long created variation across provinces in access to needed treatments and has contributed to persistent cost growth in both the private and public sectors. Among the recommendations of the 2002 Romanow Commission was a proposed national standard for "last-dollar" pharmacare that would cover any household's drug costs beyond a high annual deductible. Such a program contrasts with the "first-dollar" pharmacare programs currently available for vulnerable populations (e.g., seniors and social assistance recipients) in most provinces. While last-dollar coverage may be a valuable set toward broadening public pharmacare in Canada, there is a risk that provincial governments may interpret the coverage of catastrophic costs as the new pharmacare ideal and therefore reduce or eliminate existing programs that currently offer first-dollar benefits.

Background: Public prescription drug plans vary markedly across Canada. To address perceived inequities in coverage across provinces, the February 2003 First Ministers' Accord on Health Care Renewal committed to ensuring that all Canadians have reasonable access to catastrophic drug coverage. A national standard for "reasonable" catastrophic coverage has yet to be formally defined., Objective: To compare the private financial burdens from prescription drugs that Canadian households would face if each of the current provincial pharmacare models were adopted as the national standard., Methods: Through simulation modelling, we computed household private financial burden by applying the cost-sharing rules from provincial drug plans to a nationally representative set of 4,860 household types differing in size, age composition, income and drug expense levels. The proportions of households that would face private out-of-pocket payments exceeding critical, or catastrophic, percentages of household income were calculated., Results: Private financial burden due to prescription drug costs varies considerably across provincial pharmacare models. Comprehensive, tax-financed pharmacare models that limit out-of-pocket expenditures to a given percentage of income, such as those found in British Columbia, Saskatchewan, Manitoba and Ontario, provide the greatest protection against catastrophic prescription drug costs. There appears, however, to be no "gold standard" for an acceptable financial burden to be borne by patients.

Canada's provincial governments have, until relatively recently, provided virtually all seniors with generous prescription drug coverage. Managers of these programs have implemented a variety of policies to contain spending while ensuring access to necessary medicines. Some of these policies have been successful in temporarily slowing cost growth. However, the lack of comprehensive utilization management tools has resulted in ongoing spending increases that now constitute a threat to the sustainability of a public drug subsidy for Canadian seniors. Sustainable and equitable pharmacare programs require the political willingness to confront opposition to policies that will, if successful, contain program costs without obstructing access.

Objective: To quantify the relative and absolute importance of different factors contributing to increases in per capita prescription drug costs for a population of Canadian seniors., Data Sources/study Setting: Data consist of every prescription claim from 1985 to 1999 for the British Columbia Pharmacare Plan A, a tax-financed public drug plan covering all community-dwelling British Columbians aged 65 and older., Study Design: Changes in per capita prescription drug expenditures are attributed to changes to four components of expenditure inflation: (1) the pattern of exposure to drugs across therapeutic categories; (2) the mix of drugs used within therapeutic categories; (3) the rate of generic drug product selection; and (4) the prices of unchanged products., Data Collection/extraction Methods: Data were extracted from administrative claims files housed at the UBC Centre for Health Services and Policy Research., Principal Findings: Changes in drug prices, the pattern of exposure to drugs across therapeutic categories, and the mix of drugs used within therapeutic categories all caused spending per capita to increase. Incentives for generic substitution and therapeutic reference pricing policies temporarily slowed the cost-increasing influence of changes in product selection by encouraging the use of generic drug products and/or cost-effective brand-name products within therapeutic categories., Conclusions: The results suggest that drug plans (and patients) would benefit from more concerted efforts to evaluate the relative cost-effectiveness of competing products within therapeutic categories of drugs.