Katja M. Hakkarainen

Percentage of Patients with Preventable Adverse Drug Reactions and Preventability of Adverse Drug Reactions – A Meta-Analysis

Background Numerous observational studies suggest that preventable adverse drug reactions are a significant burden in healthcare, but no meta-analysis using a standardised definition for adverse drug reactions exists. The aim of the study was to estimate the percentage of patients with preventable adverse drug reactions and the preventability of adverse drug reactions in adult outpatients and inpatients. Methods Studies were identified through searching Cochrane, CINAHL, EMBASE, IPA, Medline, PsycINFO and Web of Science in September 2010, and by hand searching the reference lists of identified papers. Original peer-reviewed research articles in English that defined adverse drug reactions according to WHO’s or similar definition and assessed preventability were included. Disease or treatment specific studies were excluded. Meta-analysis on the percentage of patients with preventable adverse drug reactions and the preventability of adverse drug reactions was conducted. Results Data were analysed from 16 original studies on outpatients with 48797 emergency visits or hospital admissions and from 8 studies involving 24128 inpatients. No studies in primary care were identified. Among adult outpatients, 2.0% (95% confidence interval (CI): 1.2–3.2%) had preventable adverse drug reactions and 52% (95% CI: 42–62%) of adverse drug reactions were preventable. Among inpatients, 1.6% (95% CI: 0.1–51%) had preventable adverse drug reactions and 45% (95% CI: 33–58%) of adverse drug reactions were preventable. Conclusions This meta-analysis corroborates that preventable adverse drug reactions are a significant burden to healthcare among adult outpatients. Among both outpatients and inpatients, approximately half of adverse drug reactions are preventable, demonstrating that further evidence on prevention strategies is required. The percentage of patients with preventable adverse drug reactions among inpatients and in primary care is largely unknown and should be investigated in future research.

Methods for assessing the preventability of adverse drug events : A systematic review

AbstractBackground: Preventable adverse drug events (ADEs) are common in both outpatient and inpatient settings. However, the proportion of preventable ADEs varies considerably in different studies, even when conducted in the same setting, and methods for assessing the preventability of ADEs are diverse. Objective: The aim of this article is to identify and systematically evaluate methods for assessing the preventability of ADEs. Data sources: Seven databases (Cochrane, CINAHL, EMBASE, IPA, MEDLINE, PsycINFO and Web of Science) were searched in September 2010 utilizing the databases’ index terms and other common terminology on preventable ADEs. No limits for the years of publication were set. Reference lists of included original articles and relevant review articles were also screened. Study selection: After applying predetermined inclusion and exclusion criteria on 4161 unique citations, 142 (3.4%) original research articles were included in the review. One additional article was included from reference lists. Outcome measures of included studies had to include the frequency of ADEs and the assessment of their preventability. Studies were excluded if they focused on individuals with one specific type of treatment, medical condition, medical procedure or ADE. Data extraction: Measurement instruments for determining the preventability of ADEs in each article were extracted and unique instruments were compared. The process of assessing the preventability of ADEs was described based on reported actions taken to standardize and conduct the assessment, and on information about the reliability and validity of the assessment. Data synthesis: Eighteen unique instruments for determining the preventability of ADEs were identified. They fell under the following four groups: (i) instruments using a definition of preventability only (n=3); (ii) instruments with a definition of preventability and an assessment scale for determining preventability (n=5); (iii) instruments with specific criteria for each preventability category (n=3); and (iv) instruments with an algorithm for determining preventability (n=7). Of actions to standardize the assessment process, performing a pilot study was reported in 21 (15%), and use of a standardized protocol was reported in 18 (13%), of the included 143 articles. Preventability was assessed by physicians in 86 (60%) articles and by pharmacists in 41 (29%) articles. In 29 (20%) articles, persons conducting the assessment were described as trained for or experienced in preventability assessment. In 94 (66%) articles, more than one person assessed the preventability of each case. Among these 94 articles, assessment was done independently in 73 (51%) articles. Procedures for managing conflicting assessments were diverse. The reliability of the preventability assessment was tested in 39 (27%) articles, and 16 (11%) articles referred to a previous reliability assessment. Reliability ranged from poor to excellent (kappa 0.19–0.98; overall agreement 26–97%). Four (3%) articles mentioned assessing validity, but no sensitivity or specificity analyses or negative or positive predictive values were presented. Conclusions: Instruments for assessing the preventability of ADEs vary from implicit instruments to explicit algorithms. There is limited evidence for the validity of the identified instruments, and instrument reliability varied significantly. The process of assessing the preventability of ADEs is also commonly imprecisely described, which hinders the interpretation and comparison of studies. For measuring the preventability of ADEs more accurately and precisely in future, we believe that existing instruments should be further studied and developed, or that one or more new instruments should be developed, and the validity and reliability of the existing and new instruments be established.

Prevalence and perceived preventability of self-reported adverse drug events--a population-based survey of 7099 adults.

Purpose Adverse drug events (ADEs) are common and often preventable among inpatients, but self-reported ADEs have not been investigated in a representative sample of the general public. The objectives of this study were to estimate the 1-month prevalence of self-reported ADEs among the adult general public, and the perceived preventability of 2 ADE categories: adverse drug reactions (ADRs) and sub-therapeutic effects (STEs). Methods In this cross-sectional study, a postal survey was sent in October 2010 to a random sample of 13 931 Swedish residents aged ≥18 years. Self-reported ADEs experienced during the past month included ADRs, STEs, drug dependence, drug intoxications and morbidity due to drug-related untreated indication. ADEs could be associated with prescription, non-prescription or herbal drugs. The respondents estimated whether ADRs and STEs could have been prevented. ADE prevalences in age groups (18–44, 45–64, or ≥65 years) were compared. Results Of 7099 respondents (response rate 51.0%), ADEs were reported by 19.4% (95% confidence interval, 18.5–20.3%), and the prevalence did not differ by age group (p>0.05). The prevalences of self-reported ADRs, STEs, and morbidities due to drug-related untreated indications were 7.8% (7.2–8.4%), 7.6% (7.0–8.2%) and 8.1% (7.5–8.7%), respectively. The prevalence of self-reported drug dependence was 2.2% (1.9–2.6%), and drug intoxications 0.2% (0.1–0.3%). The respondents considered 19.2% (14.8–23.6%) of ADRs and STEs preventable. Although reported drugs varied between ADE categories, most ADEs were attributable to commonly dispensed drugs. Drugs reported for all and preventable events were similar. Conclusions One-fifth of the adult general public across age groups reported ADEs during the past month, indicating a need for prevention strategies beyond hospitalised patients. For this, the underlying causes of ADEs should increasingly be investigated. The high burden of ADEs and preventable ADEs from widely used drugs across care settings supports redesigning a safer healthcare system to adequately tackle the problem.

Economic Impact of Adverse Drug Events - A Retrospective Population-Based Cohort Study of 4970 Adults

Background The aim was to estimate the direct costs caused by ADEs, including costs for dispensed drugs, primary care, other outpatient care, and inpatient care, and to relate the direct costs caused by ADEs to the societal COI (direct and indirect costs), for patients with ADEs and for the entire study population. Methods We conducted a population-based observational retrospective cohort study of ADEs identified from medical records. From a random sample of 5025 adults in a Swedish county council, 4970 were included in the analyses. During a three-month study period in 2008, direct and indirect costs were estimated from resource use identified in the medical records and from register data on costs for resource use. Results Among 596 patients with ADEs, the average direct costs per patient caused by ADEs were USD 444.9 [95% CI: 264.4 to 625.3], corresponding to USD 21 million per 100 000 adult inhabitants per year. Inpatient care accounted for 53.9% of all direct costs caused by ADEs. For patients with ADEs, the average societal cost of illness was USD 6235.0 [5442.8 to 7027.2], of which direct costs were USD 2830.1 [2260.7 to 3399.4] (45%), and indirect costs USD 3404.9 [2899.3 to 3910.4] (55%). The societal cost of illness was higher for patients with ADEs compared to other patients. ADEs caused 9.5% of all direct healthcare costs in the study population. Conclusions Healthcare costs for patients with ADEs are substantial across different settings; in primary care, other outpatient care and inpatient care. Hence the economic impact of ADEs will be underestimated in studies focusing on inpatient ADEs alone. Moreover, the high proportion of indirect costs in the societal COI for patients with ADEs suggests that the observed costs caused by ADEs would be even higher if including indirect costs. Additional studies are needed to identify interventions to prevent and manage ADEs.

Prevalence, nature and potential preventability of adverse drug events – a population-based medical record study of 4970 adults

Aims To estimate the 3 month prevalence of adverse drug events (ADEs), categories of ADEs and preventable ADEs, and the preventability of ADEs among adults in Sweden. Further, to identify drug classes and organ systems associated with ADEs and estimate their seriousness. Methods A random sample of 5025 adults in a Swedish county council in 2008 was drawn from the Total Population Register. All their medical records in 29 inpatient care departments in three hospitals, 110 specialized outpatient clinics and 51 primary care units were reviewed retrospectively in a stepwise manner, and complemented with register data on dispensed drugs. ADEs, including adverse drug reactions (ADRs), sub-therapeutic effects of drug therapy (STEs), drug dependence and abuse, drug intoxications from overdose, and morbidities due to drug-related untreated indication, were detected during a 3 month study period, and assessed for preventability. Results Among 4970 included individuals, the prevalence of ADEs was 12.0% (95% confidence interval (CI) 11.1, 12.9%), and preventable ADEs 5.6% (95% CI 5.0, 6.2%). ADRs (6.9%; 95% CI 6.2, 7.6%) and STEs (6.4%; 95% CI 5.8, 7.1%) were more prevalent than the other ADEs. Of the ADEs, 38.8% (95% CI 35.8–41.9%) was preventable, varying by ADE category and seriousness. ADEs were frequently associated with nervous system and cardiovascular drugs, but the associated drugs and affected organs varied by ADE category. Conclusions The considerable burden of ADEs and preventable ADEs from commonly used drugs across care settings warrants large-scale efforts to redesign safer, higher quality healthcare systems. The heterogeneous nature of the ADE categories should be considered in research and clinical practice for preventing, detecting and mitigating ADEs.

Preventable drug related mortality in a Swedish population

Several studies indicate that the medical burden of fatal adverse drug reactions (FADRs) is significant, but the preventability of FADRs in the general population is largely unknown. The aim of this study was to determine the proportion of preventable FADRs and preventable fatal drug poisonings (FDPs) in a Swedish population.

Modelling drug-related morbidity in Sweden using an expert panel of physicians

PurposeIn modelling studies using pharmacists’ opinions, drug-related morbidity (DRM) and preventable DRM have been more common than in observational studies, and the resulting costs are extensive. Modelling studies’ estimates may vary depending on informants’ profession. The purpose of this modelling study was to estimate the proportion of patients with DRM and preventable DRM and the cost of illness (COI) of DRM in Sweden based on physicians’ expert opinions.MethodA conceptual model of DRM was modified from previous studies. Using a modified Delphi technique, a panel of physicians (n = 19) estimated the probabilities of DRM, preventable DRM, and clinical outcomes of DRM separately for outpatients and inpatients. DRM included new medical problems (adverse drug reactions, drug dependence, and intoxications by overdose) and therapeutic failure (insufficient effects of medicines, and morbidity due to untreated indication). A COI analysis included the direct costs of DRM.ResultsPhysicians estimated that 51 ± 22% [mean ± standard deviation (SD)] of outpatients experience DRM and 12 ± 8% preventable DRM. Of inpatients, 54 ± 17% was estimated to experience DRM and 16 ± 7% preventable DRM. Of outpatients with DRM, 24 ± 11% was estimated to experience preventable DRM, whereas this proportion for inpatients was 31 ± 15%. The estimated COI was 376 euros per outpatient and 838 euros per inpatient.ConclusionsSwedish physicians estimated that every other outpatient and inpatient experiences DRM, which is often preventable and costly. As physicians’ estimates on the proportion of patients with DRM were higher than in observational studies in restricted subpopulations, DRM may be more common in the general population than observational studies suggest.

Refill adherence and self-reported adverse drug reactions and sub-therapeutic effects: a population-based study†

To assess refill adherence to dispensed oral long‐term medications among the adult population and to investigate whether the percentages of self‐reported adverse drug reactions (ADRs) and sub‐therapeutic effects (STEs) differed for medications with adequate refill adherence, oversupply, and undersupply.

Direct and indirect costs for adverse drug events identified in medical records across care levels, and their distribution among payers

Background: Adverse drug events (ADEs) cause considerable costs in hospitals. However, little is known about costs caused by ADEs outside hospitals, effects on productivity, and how the costs are distributed among payers. Objective: To describe the direct and indirect costs caused by ADEs, and their distribution among payers. Furthermore, to describe the distribution of patient out‐of‐pocket costs and lost productivity caused by ADEs according to socio‐economic characteristics. Method: In a random sample of 5025 adults in a Swedish county, prevalence‐based costs for ADEs were calculated. Two different methods were used: 1) based on resource use judged to be caused by ADEs, and 2) as costs attributable to ADEs by comparing costs among individuals with ADEs to costs among matched controls. Payers of costs caused by ADEs were identified in medical records among those with ADEs (n = 596), and costs caused to individual patients were described by socio‐economic characteristics. Results: Costs for resource use caused by ADEs were &U20AC;505 per patient with ADEs (95% confidence interval &U20AC;345–665), of which 38% were indirect costs. Compared to matched controls, the costs attributable to ADEs were &U20AC;1631, of which &U20AC;410 were indirect costs. The local health authorities paid 58% of the costs caused by ADEs. Women had higher productivity loss than men (&U20AC;426 vs. &U20AC;109, p = 0.018). Out‐of‐pocket costs displaced a larger proportion of the disposable income among low‐income earners than higher income earners (0.7% vs. 0.2%–0.3%). Conclusion: We used two methods to identify costs for ADEs, both identifying indirect costs as an important component of the overall costs for ADEs. Although the largest payers of costs caused by ADEs were the local health authorities responsible for direct costs, employers and patients costs for lost productivity contributed substantially. Our results indicate inequalities in costs caused by ADEs, by sex and income. HighlightsIndirect costs contributed to the overall costs for adverse drug events, even when limited to time spent in healthcare.Adverse drug events and their consequences are a burden throughout the society and not limited to local health authorities.We found inequalities in the distribution of costs caused by adverse drug events in Sweden, by sex and by income.

Pharmacoepidemiology at Nordic School of Public Health NHV: Examples from 1999 to 2014

Background: Pharmacoepidemiology is a branch of public health and had a place at the Nordic School of Public Health. Courses, Master’s theses and Doctorates of Public Health (DrPH) in Pharmacoepidemiology were a relatively minor, but still important part of the school’s activities. Methods: This paper gives a short background, followed by some snapshots of the activities at NHV, and then some illustrative case-studies. These case-studies list their own responsible co-authors and have separate reference lists. Results: In the Nordic context, NHV was a unique provider of training and research in pharmacoepidemiology, with single courses to complete DrPH training, as well as implementation of externally-funded research projects. Conclusions: With the closure of NHV at the end of 2014, it is unclear if such a comprehensive approach towards pharmacoepidemiology will be found elsewhere in the Nordic countries.