Effectiveness of mRNA COVID-19 Monovalent and Bivalent Vaccine Booster Doses Against Omicron Severe Outcomes Among Adults Aged ≥50 Years in Ontario, Canada: A Canadian Immunization Research Network Study.

We estimated the effectiveness of booster doses of monovalent and bivalent mRNA COVID-19 vaccines against Omicron-associated severe outcomes among adults aged ≥50 years in Ontario, Canada. Monovalent and bivalent mRNA COVID-19 booster doses provided similar strong initial protection against severe outcomes. Uncertainty remains around waning of protection from these vaccines.

Opioid-related deaths between 2019 and 2021 across 9 Canadian provinces and territories.

BACKGROUND: The drug toxicity crisis continues to accelerate across Canada, with rapid increases in opioid-related harms following the onset of the COVID-19 pandemic. We sought to describe trends in the burden of opioid-related deaths across Canada throughout the pandemic, comparing these trends by province or territory, age, and sex. METHODS: We conducted a repeated cross-sectional analysis of accidental opioid-related deaths between Jan. 1, 2019, and Dec. 31, 2021, across 9 Canadian provinces and territories using aggregated national data. Our primary measure was the burden of premature opioid-related death, measured by potential years of life lost. Our secondary measure was the proportion of all deaths attributable to opioids; we used the Cochrane-Armitage test for trend to compare proportions. RESULTS: Between 2019 and 2021, the annual number of opioid-related deaths increased from 3007 to 6222 and years of life lost increased from 126 115 to 256 336 (from 3.5 to 7.0 yr of life lost per 1000 population). In 2021, the highest number of years of life lost was among males (181 525 yr) and people aged 30-39 years (87 045 yr). In 2019, we found that 1.7% of all deaths among those younger than 85 years were related to opioids, rising to 3.2% in 2021. Significant increases in the proportion of deaths related to opioids were observed across all age groups (p < 0.001), representing 29.3% and 29.0% of deaths among people aged 20-29 and 30-39 years in 2021, respectively. INTERPRETATION: Across Canada, the burden of premature opioid-related deaths doubled between 2019 and 2021, representing more than one-quarter of deaths among younger adults. The disproportionate loss of life in this demographic group highlights the critical need for targeted prevention efforts.

Characteristics of primary care practices by proportion of patients unvaccinated against SARS-CoV-2: a cross-sectional cohort study.

BACKGROUND: Variations in primary care practices may explain some differences in health outcomes during the COVID-19 pandemic. We sought to evaluate the characteristics of primary care practices by the proportion of patients unvaccinated against SARS-CoV-2. METHODS: We conducted a population-based, cross-sectional cohort study using linked administrative data sets in Ontario, Canada. We calculated the percentage of patients unvaccinated against SARS-CoV-2 enrolled with each comprehensive-care family physician, ranked physicians according to the proportion of patients unvaccinated, and identified physicians in the top 10% (v. the other 90%). We compared characteristics of family physicians and their patients in these 2 groups using standardized differences. RESULTS: We analyzed 9060 family physicians with 10 837 909 enrolled patients. Family physicians with the largest proportion (top 10%) of unvaccinated patients (n = 906) were more likely to be male, to have trained outside of Canada, to be older, and to work in an enhanced fee-for-service model than those in the remaining 90%. Vaccine coverage (≥ 2 doses of SARS-CoV-2 vaccine) was 74% among patients of physicians with the largest proportion of unvaccinated patients, compared with 87% in the remaining patient population. Patients in the top 10% group tended to be younger and live in areas with higher levels of ethnic diversity and immigration and lower incomes. INTERPRETATION: Primary care practices with the largest proportion of patients unvaccinated against SARS-CoV-2 served marginalized communities and were less likely to use team-based care models. These findings can guide resource planning and help tailor interventions to integrate public health priorities within primary care practices.

Effects of the valsartan recall on heart failure patients: A nationwide analysis.

BACKGROUND: Valsartan is commonly used for cardiac conditions. In 2018, the Food and Drug Administration recalled generic valsartan due to the detection of impurities. Our objective was to determine if heart failure patients receiving valsartan at the recall date had a greater likelihood of unfavorable outcomes than patients using comparable antihypertensives. METHODS: We conducted a cohort study of Optum's de-identified Clinformatics® Datamart (July 2017-January 2019). Heart failure patients with commercial or Medicare Advantage insurance who received valsartan were compared to persons who received non-recalled angiotensin receptor blockers (ARBs) and angiotensin converting enzyme-inhibitors (ACE-Is) for 1 year prior and including the recall date. Outcomes included a composite for all-cause hospitalization, emergency department (ED), and urgent care (UC) use and a measure of cardiac events which included hospitalizations for acute myocardial infarction and hospitalizations/ED/UC visits for stroke/transient ischemic attack, heart failure or hypertension at 6-months post-recall. Cox proportional hazard models with propensity score weighting compared the risk of outcomes between groups. RESULTS: Of the 87 130 adherent patients, 15% were valsartan users and 85% were users of non-recalled ARBs/ACE-Is. Valsartan use was not associated with an increased risk of all-cause hospitalization/ED/UC use six-months post-recall (HR 1.00; 95% CI 0.96-1.03), compared with individuals taking non-recalled ARBs/ACE-Is. Similarly, cardiac events 6-months post-recall did not differ between individuals on valsartan and non-recalled ARBs/ACE-Is (HR 1.04; 95% CI 0.97-1.12). CONCLUSIONS: The valsartan recall did not affect short-term outcomes of heart failure patients. However, the recall potentially disrupted the medication regimens of patients, possibly straining the healthcare system.

Patterns of publicly funded naltrexone use among patients diagnosed with alcohol use disorder in Ontario.

AIMS: Naltrexone is recommended first-line to manage alcohol use disorder (AUD). With previous studies indicating poor retention on naltrexone, we determined duration of naltrexone use and assessed the association between prescription setting and time to discontinuation in Ontario. METHODS: We conducted a retrospective population-based cohort study among Ontario public drug beneficiaries diagnosed with AUD who initiated publicly funded naltrexone from June 2018 to September 2019. The primary outcome was time to naltrexone discontinuation, with a secondary analysis assessing receipt of at least one prescription refill. We used Cox proportional hazards models and logistic regression to test the association between prescription setting and each medication persistence outcome. RESULTS: Among 2531 new naltrexone patients with AUD, the median duration of naltrexone use was 31 days and 394 (15.6%) continued naltrexone for 6 months or longer. There was no association between setting of initiation and duration of naltrexone use; however, those initiating naltrexone following an acute inpatient hospital stay were more likely to fill a second prescription (aOR 1.43, 95% CI 0.96-2.14), while those initiating after an ED visit were less likely to be dispensed a second prescription (aOR = 0.69, 95% CI 0.52-0.90) compared to those starting in a physician's office. CONCLUSION: Persistence on naltrexone to treat an AUD is low, regardless of the setting of initiation. Further research is needed to elucidate the barriers encountered by patients with AUD that lead to poor treatment persistence in order to develop interventions that facilitate patient-centered access to evidence-based treatment for AUD in the province.

Examining the impact of the COVID-19 pandemic on homecare services among individuals with traumatic and non-traumatic spinal cord injuries.

STUDY DESIGN: Descriptive repeated-cross sectional retrospective longitudinal cohort study. OBJECTIVE: To investigate the impact of the COVID-19 pandemic on homecare services in individuals with traumatic or non-traumatic Spinal Cord Injury (SCI). SETTING: Health administrative database in Ontario, Canada. METHODS: A repeated cross-sectional study using linked health administrative databases from March 2015 to June 2022. Monthly homecare utilization was assessed in 3381 adults with SCI using Autoregressive Integrated Moving Average (ARIMA) models. RESULTS: Compared to pre-pandemic levels, between March 2020 to June 2022, the traumatic group experienced a decrease in personal and/or homemaking services, as well as an increase in nursing visits from April 2020-March 2022 and June 2022. Case management increased at various times for the traumatic group, however therapies decreased in May 2020 only. The non-traumatic group experienced a decrease in personal and/or homemaking services in July 2020, as well as an increase in nursing visits from March 2020 to February 2021 and sporadically throughout 2020. Case management also increased at certain points for the non-traumatic group, but therapies decreased in April 2020, July 2020, and September 2021. CONCLUSION: The traumatic group had decreases in personal and/or homemaking services. Both groups had increases in nursing services, increases in case management, and minimal decreases in therapies at varying times during the pandemic. Investigation is warranted to understand the root cause of these changes, and if they resulted in adverse outcomes.

Impact of COVID-19 pandemic on prescription stimulant use among children and youth: a population-based study.

COVID-19 associated public health measures and school closures exacerbated symptoms in some children and youth with attention-deficit hyperactivity disorder (ADHD). Less well understood is how the pandemic influenced patterns of prescription stimulant use. We conducted a population-based study of stimulant dispensing to children and youth ≤ 24 years old between January 1, 2013, and June 30, 2022. We used structural break analyses to identify the pandemic month(s) when changes in the dispensing of stimulants occurred. We used interrupted time series models to quantify changes in dispensing following the structural break and compare observed and expected stimulant use. Our main outcome was the change in the monthly rate of stimulant use per 100,000 children and youth. Following an initial immediate decline of 60.1 individuals per 100,000 (95% confidence interval [CI] - 99.0 to - 21.2), the monthly rate of stimulant dispensing increased by 11.8 individuals per 100,000 (95% CI 10.0-13.6), with the greatest increases in trend observed among females, individuals in the highest income neighbourhoods, and those aged 20 to 24. Observed rates were between 3.9% (95% CI 1.7-6.2%) and 36.9% (95% CI 34.3-39.5%) higher than predicted among females from June 2020 onward and between 7.1% (95% CI 4.2-10.0%) and 50.7% (95% CI 47.0-54.4%) higher than expected among individuals aged 20-24 from May 2020 onward. Additional research is needed to ascertain the appropriateness of stimulant use and to develop strategies supporting children and youth with ADHD during future periods of long-term stressors.

Effectiveness of Coronavirus Disease 2019 Vaccines Against Hospitalization and Death in Canada: A Multiprovincial, Test-Negative Design Study.

BACKGROUND: A major goal of coronavirus disease 2019 (COVID-19) vaccination is to prevent severe outcomes (hospitalizations and deaths). We estimated the effectiveness of messenger RNA (mRNA) and ChAdOx1 COVID-19 vaccines against severe outcomes in 4 Canadian provinces between December 2020 and September 2021. METHODS: We conducted this multiprovincial, retrospective, test-negative study among community-dwelling adults aged ≥18 years in Ontario, Quebec, British Columbia, and Manitoba using linked provincial databases and a common study protocol. Multivariable logistic regression was used to estimate province-specific vaccine effectiveness against COVID-19 hospitalization and/or death. Estimates were pooled using random-effects models. RESULTS: We included 2 508 296 tested participants, with 31 776 COVID-19 hospitalizations and 5842 deaths. Vaccine effectiveness was 83% after a first dose and 98% after a second dose against both hospitalization and death (separately). Against severe outcomes, effectiveness was 87% (95% confidence interval [CI], 71%-94%) ≥84 days after a first dose of mRNA vaccine, increasing to 98% (95% CI, 96%-99%) ≥112 days after a second dose. Vaccine effectiveness against severe outcomes for ChAdOx1 was 88% (95% CI, 75%-94%) ≥56 days after a first dose, increasing to 97% (95% CI, 91%-99%) ≥56 days after a second dose. Lower 1-dose effectiveness was observed for adults aged ≥80 years and those with comorbidities, but effectiveness became comparable after a second dose. Two doses of vaccines provided very high protection for both homologous and heterologous schedules and against Alpha, Gamma, and Delta variants. CONCLUSIONS: Two doses of mRNA or ChAdOx1 vaccine provide excellent protection against severe outcomes.

Protection conferred by COVID-19 vaccination, prior SARS-CoV-2 infection, or hybrid immunity against Omicron-associated severe outcomes among community-dwelling adults.

INTRODUCTION: We assessed protection from COVID-19 vaccines and/or prior SARS-CoV-2 infection against Omicron-associated severe outcomes during successive sublineage-predominant periods. METHODS: We used a test-negative design to estimate protection by vaccines and/or prior infection against hospitalization/death among community-dwelling, PCR-tested adults aged ≥50 years in Ontario, Canada between January 2, 2022 and June 30, 2023. Multivariable logistic regression was used to estimate the relative change in the odds of hospitalization/death with each vaccine dose (2-5) and/or prior PCR-confirmed SARS-CoV-2 infection (compared with unvaccinated, uninfected subjects) up to 15 months since the last vaccination or infection. RESULTS: We included 18,526 cases with Omicron-associated severe outcomes and 90,778 test-negative controls. Vaccine protection was high during BA.1/BA.2 predominance, but was generally <50% during periods of BA.4/BA.5 and BQ/XBB predominance without boosters. A third/fourth dose transiently increased protection during BA.4/BA.5 predominance (third-dose, 6-month: 68%, 95%CI 63%-72%; fourth-dose, 6-month: 80%, 95%CI 77%-83%), but was lower and waned quickly during BQ/XBB predominance (third-dose, 6-month: 59%, 95%CI 48%-67%; 12-month: 49%, 95%CI 41%-56%; fourth-dose, 6-month: 62%, 95%CI 56%-68%, 12-months: 51%, 95%CI 41%-56%). Hybrid immunity conferred nearly 90% protection throughout BA.1/BA.2 and BA.4/BA.5 predominance, but was reduced during BQ/XBB predominance (third-dose, 6-month: 60%, 95%CI 36%-75%; fourth-dose, 6-month: 63%, 95%CI 42%-76%). Protection was restored with a fifth dose (bivalent; 6-month: 91%, 95%CI 79%-96%). Prior infection alone did not confer lasting protection. CONCLUSION: Protection from COVID-19 vaccines and/or prior SARS-CoV-2 infections against severe outcomes is reduced when immune-evasive variants/subvariants emerge and may also wane over time. Our findings support a variant-adapted booster vaccination strategy with periodic review.

Up-to-date on cancer screening among Ontario patients seen by walk-in clinic physicians: A retrospective cohort study.

Walk-in clinics are typically viewed as high-volume locations for managing acute issues but also may serve as a location for primary care, including cancer screening, for patients without a family physician. In this population-based cohort study, we compared breast, cervical and colorectal cancer screening up-to-date status for people living in the Canadian province of Ontario who were formally enrolled to a family physician versus those not enrolled but who had at least one encounter with a walk-in clinic physician in the previous year. Using provincial administrative databases, we created two mutually exclusive groups: i) those who were formally enrolled to a family physician, ii) those who were not enrolled but had at least one visit with a walk-in clinic physician from April 1, 2019 to March 31, 2020. We compared up to date status for three cancer screenings as of April 1, 2020 among screen-eligible people. We found that people who were not enrolled and had seen a walk-in clinic physician in the previous year consistently were less likely to be up to date on cancer screening than Ontarians who were formally enrolled with a family physician (46.1% vs. 67.4% for breast, 45.8% vs. 67.4% for cervical, 49.5% vs. 73.1% for colorectal). They were also more likely to be foreign-born and to live in structurally marginalized neighbourhoods. New methods are needed to enable screening for people who are reliant on walk-in clinics and to address the urgent need in Ontario for more primary care providers who deliver comprehensive, longitudinal care.

Prevalence and predictors of primary nonadherence to medications prescribed in primary care.

BACKGROUND: Most research on medication adherence has focused on secondary nonadherence and persistence to therapy. Medication prescriptions that are never filled by patients (primary nonadherence) remain understudied in the general population. METHODS: We linked prescribing data from primary care electronic medical records to comprehensive pharmacy dispensing claims between January 2013 and April 2019 in British Columbia (BC) to estimate primary nonadherence, defined as failure to dispense a new medication or its equivalent within 6 months of the prescription date. We used hierarchical multivariable logistic regression to determine prescriber, patient and medication factors associated with primary nonadherence among community-dwelling patients in primary care. RESULTS: Among 150 565 new prescriptions to 34 243 patients, 17% of prescriptions were never filled. Primary nonadherence was highest for drugs prescribed mostly on an as-needed basis, including topical corticosteroids (35.1%) and antihistamines (23.4%). In multivariable analysis, primary nonadherence was lower for prescriptions issued by male prescribers (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.50-0.88). Primary nonadherence decreased with patient age (OR 0.91, 95% CI 0.90-0.92 for each additional 10 years) but increased with polypharmacy among patients aged 65 years or older. Patients filled more than 82% of their medication prescriptions within 2 weeks after their primary care provider visit. INTERPRETATION: The prevalence of primary nonadherence to new prescriptions was 17%. Interventions to address primary nonadherence could target older patients with multiple medication use and within the first 2 weeks of the prescription issue date.

Prevalence and nature of manufacturer-sponsored patient support programs for prescription drugs in Canada: a cross-sectional study.

BACKGROUND: Globally, pharmaceutical companies offer patient support programs in tandem with their products, which aim to enhance medication adherence and patient experience through education, training, support and financial assistance. We sought to identify the proportion and characteristics of such patient support programs in Canada and to describe the nature of supports provided. METHODS: We conducted a crosssectional study to identify and characterize all marketed prescription drugs available in Canada as of Aug. 23, 2022, using the Health Canada Drug Product and CompuScript databases. To describe the nature of supports provided, we conducted a content analysis of publicly available patient support program websites and Web-based documents. Using logistic regression, we identified characteristics of drugs associated with having a patient support program including brand-name or branded generic (generic medications with a proprietary name), orphan (medications for rare diseases) or biologic drug status; estimated total cost of prescriptions dispensed at retail pharmacies; and price per unit. RESULTS: Of the 2556 prescription drugs marketed by 89 companies in the study period, 256 (10.0%) had a patient support program in Canada. Many of the 89 drug manufacturers (n = 55, 61.8%) offered at least 1 patient support program, frequently relying on third-party administrators for delivery. Brandname and branded generic medications, biologic agents and drugs with orphan status were more likely to have a patient support program than generic drugs. Compared with drugs priced $1.01-$10.00 per unit, drugs priced $10.01-$100.00 per unit were nearly 8 times more likely to have a patient support program (adjusted odds ratio 7.54, 95% confidence interval 4.07- 14.64). Most sampled patient support programs included reimbursement navigation (n = 231, 90.2%) and clinical case management (n = 223, 87.1%). INTERPRETATION: About 1 in 10 drugs marketed in Canada has a manufacturersponsored patient support program, but these are concentrated around brand-name, branded generic, biologic and high-cost drugs, often for rare diseases. To understand the impact of patient support programs on health outcomes and sustainable access to cost-effective medicines, greater transparency and independent evaluation of patient support programs is necessary.

Population-based evaluation of the effectiveness of nirmatrelvir-ritonavir for reducing hospital admissions and mortality from COVID-19.

BACKGROUND: A randomized controlled trial involving a high-risk, unvaccinated population that was conducted before the Omicron variant emerged found that nirmatrelvir-ritonavir was effective in preventing progression to severe COVID-19. Our objective was to evaluate the effectiveness of nirmatrelvir-ritonavir in preventing severe COVID-19 while Omicron and its subvariants predominate. METHODS: We conducted a population-based cohort study in Ontario that included all residents who were older than 17 years of age and had a positive polymerase chain reaction test for SARS-CoV-2 between Apr. 4 and Aug. 31, 2022. We compared patients treated with nirmatrelvir-ritonavir with patients who were not treated and measured the primary outcome of hospital admission from COVID-19 or all-cause death at 1-30 days, and a secondary outcome of all-cause death. We used weighted logistic regression to calculate weighted odds ratios (ORs) with confidence intervals (CIs) using inverse probability of treatment weighting (IPTW) to control for confounding. RESULTS: The final cohort included 177 545 patients, 8876 (5.0%) who were treated with nirmatrelvir-ritonavir and 168 669 (95.0%) who were not treated. The groups were well balanced with respect to demographic and clinical characteristics after applying stabilized IPTW. We found that the occurrence of hospital admission or death was lower in the group given nirmatrelvir-ritonavir than in those who were not (2.1% v. 3.7%; weighted OR 0.56, 95% CI 0.47-0.67). For death alone, the weighted OR was 0.49 (95% CI 0.39-0.62). Our findings were similar across strata of age, drug-drug interactions, vaccination status and comorbidities. The number needed to treat to prevent 1 case of severe COVID-19 was 62 (95% CI 43-80), which varied across strata. INTERPRETATION: Nirmatrelvir-ritonavir was associated with significantly reduced odds of hospital admission and death from COVID-19, which supports use to treat patients with mild COVID-19 who are at risk for severe disease.

A comparison of family physician and dermatologist topical corticosteroid prescriptions: A population-based cross-sectional study.

BACKGROUND: Topical corticosteroids (TCS) are commonly prescribed to treat inflammatory skin diseases, and appropriate prescription is necessary for treatment success. OBJECTIVE: To quantify differences between TCS prescribed by dermatologists at consultation and family physicians for patients treated for any skin condition. METHODS: Using administrative health data in Ontario, we included all Ontario Drug Benefit recipients who filled at least one TCS prescription from a dermatologist at consultation and a family physician in the year prior between January 2014 and December 2019. We estimated mean differences and 95% confidence intervals in amount (in grams) and potency between the index dermatologist prescription and the highest and most recent family physician prescription amounts and potencies in the preceding year using linear mixed-effect models. RESULTS: A total of 69,335 persons were included. The mean dermatologist amount was 34% larger than the highest amount and 54% larger than the most recent amount prescribed by family physicians. There were small but statistically significant differences in potency using established 7-category and 4-category potency classification systems. CONCLUSIONS: Compared to family physicians, dermatologists prescribed substantially larger amounts and similarly potent TCS at consultation. Further research is needed to determine the effect of these differences on clinical outcomes.

Accessing hepatitis C direct acting antivirals among people living with hepatitis C: a qualitative study.

BACKGROUND: Hepatitis C is curable with direct-acting antivirals (DAAs). However, treatment uptake remains low among marginalized populations such as people who inject drugs. We sought to understand challenges to treatment uptake with DAAs among people living with hepatitis C and compare treatment experiences between people who do and do not inject prescription and/or unregulated drugs. METHODS: We conducted a qualitative study using focus groups with 23 adults aged 18 years and over who completed DAA treatment or were about to begin such treatment at the time of the study. Participants were recruited from hepatitis C treatment clinics across Toronto, Ontario. We drew upon stigma theory to interpret participants' accounts. RESULTS: Following analysis and interpretation, we generated five theoretically-informed themes characterizing the experiences of individuals accessing DAAs: "being 'worthy' of the cure", "spatially enacted stigma", "countering social and structural vulnerability: the importance of peers", "identity disruption and contagion: attaining a 'social cure'" and "challenging stigma with population-based screening". Overall, our findings suggest that structural stigma generated and reproduced through healthcare encounters limits access to DAAs among people who inject drugs. Peer-based programs and population-based screening were proposed by participants as mechanisms for countering stigma within health care settings and 'normalizing' hepatitis C among the general population. CONCLUSIONS: Despite the availability of curative therapies, access to such treatment for people who inject drugs is limited by stigma enacted in and structured within healthcare encounters. Developing novel, low-threshold delivery programs that remove power differentials and attend to the social and structural determinants of health and reinfection are needed to facilitate further scale up of DAAs and support the goal of eradicating hepatitis C as a public health threat.

Feasibility and validity of using healthcare databases to conduct cross-national comparative studies of opioid use, its determinants and consequences.

PURPOSE: A cross-national comparative (CNC) study about opioid utilization would allow the identification of strategies to improve pain management and mitigate risk. However, little is known about the accessibility and validity of information in healthcare databases internationally. This study aimed to identify the feasibility of using healthcare databases to conduct a CNC study of opioid utilization and its associated consequences. METHODS: A cross-sectional survey was launched in March 2018, including experts interested in CNC studies comparing opioid utilization by purposeful sampling. An electronic survey was used to collect database characteristics, medicine information, and linkage information of each aggregate-level dataset (AD) and individual patient-level dataset (IPD). RESULTS: Overall, participants from 21 geographical regions reported 18 ADs and 19 IPDs. Information on dispensed medications is available from 17 ADs and 17 IPDs. Of the 16 ADs that include primary care settings, only 9 ADs can obtain information from secondary care settings. Fourteen IPDs included patients' characteristics or could be retrieved from linkage databases. Although most ADs are publicly accessible (n = 13), only five IPDs can be accessed without extra cost. CONCLUSION: Most ADs could be used to report opioid utilization in a primary care setting. IPDs with linkage databases should be applied to identify potential determinants, clinical outcomes, and policy impact. Data access restrictions and governance policies across jurisdictions can be challenging for timely analysis and require further collaboration.

Evaluating the use of methods to mitigate bias from non-transient medications in the case-crossover design: A systematic review.

PURPOSE: The case-crossover design is a self-controlled study design used to compare exposure immediately preceding an event occurrence with exposure in earlier control periods. The design is most suitable for transient exposures in order to avoid biases that can be problematic when using the case-crossover design for non-transient (i.e., chronic) exposures. Our goal was to conduct a systematic review of case-crossover studies and its variants (case-time-control and case-case-time-control) in order to compare design and analysis choices by medication type. METHODS: We conducted a systematic search to identify recent case-crossover, case-time-control, and case-case-time-control studies focused on medication exposures. Articles indexed in MEDLINE and EMBASE using these study designs that were published between January 2015 and December 2021 in the English language were identified. Reviews, methodological studies, commentaries, articles without medications as the exposure of interest, and articles with no available full text were excluded. Study characteristics including study design, outcome, risk window, control window, reporting of discordant pairs, and inclusion of sensitivity analyses were summarized overall and by medication type. We further evaluated the implementation of recommended methods to account for biases introduced by non-transient exposures among articles that used the case-crossover design on a non-transient exposure. RESULTS: Of the 2036 articles initially identified, 114 articles were included. The case-crossover was the most common study design (88%), followed by the case-time-control (17%), and case-case-time-control (3%). Fifty-three percent of the articles included only transient medications, 35% included only non-transient medications, and 12% included both. Across years, the proportion of case-crossover articles evaluating a non-transient medication ranged from 30% in 2018 to 69% in 2017. We found that 41% of the articles that evaluated a non-transient medication did not apply any of the recommended methods to account for biases and more than half of which were conducted by authors with no previous publication history of case-crossover studies. CONCLUSION: Using the case-crossover design to evaluate a non-transient medication remains common in pharmacoepidemiology. Researchers should apply appropriate design and analysis choices when opting to use a case-crossover design with non-transient medication exposures.

Major Shifts in Acid Suppression Drug Utilization After the 2019 Ranitidine Recalls in Canada and United States.

BACKGROUND: Drug shortages are a complex global challenge, and few studies have analyzed quantitative data on their impacts. In September 2019, detection of a nitrosamine impurity in ranitidine led to recalls and shortages. AIMS: We investigated the extent of the ranitidine shortage and its impacts on acid suppression drug utilization in Canada and the United States (US). METHODS: We conducted an interrupted time series analysis of acid suppression drug purchases in Canada and the US from 2016 through 2021 using IQVIA's MIDAS database. We used autoregressive integrated moving average models to determine the impact of the shortage on purchasing rates for ranitidine, other histamine-2 receptor antagonists (H2RAs), and proton pump inhibitors (PPIs). RESULTS: Prior to the recalls, 20,439,915 ranitidine units were purchased monthly in Canada and 189,038,496 in the US on average. After the recalls started in September 2019, purchasing rates decreased for ranitidine (Canada p = 0.0048, US p < 0.0001) and increased for non-ranitidine H2RAs (Canada p = 0.0192, US p = 0.0534). One month into the recalls, purchasing rates dropped by 99% (Canada) and 53% (US) for ranitidine and increased by 128.3% (Canada) and 37.3% (US) for non-ranitidine H2RAs. PPI purchasing rates did not change significantly in either country. CONCLUSIONS: The ranitidine shortage led to immediate and sustained shifts in H2RA utilization in both countries, potentially affecting hundreds of thousands of patients. Our results emphasize the need for future studies of the clinical and financial implications of the shortage, and the importance of ongoing work to mitigate and prevent drug shortages.

Integration of real-world evidence from different data sources in health technology assessment.

Real-world evidence (RWE) is being increasingly used by a wide range of stakeholders involved in the therapeutic product lifecycle but remains underutilized in the health technology assessment (HTA) process. RWE aims to fill the current evidence gaps, reduce the uncertainty around the benefits of medical technologies, and better understand the long-term impact of health technologies in real-world conditions. Despite the minimal use of RWE in some elements of HTA, there has been a larger push to further utilize RWE in the HTA processes. HTA bodies, as other stakeholders, work towards developing more robust means to leverage RWE from various data sources in the HTA processes. However, these agencies need to overcome important challenges before the broader incorporation of RWE into their routine practice. This paper aims to explore the extensive integration of RWE utilizing diverse sources of RWD. We discuss the utilization of RWE in HTA processes, considering aspects such as when, where, and how RWE can be effectively applied. Additionally, we seek the potential challenges and barriers associated with the utilization of different data sources.

Impact of a Publicly-Funded Pharmacare Program on Prescription Stimulant use Among Children and Youth: A Population-Based Observational Natural Experiment.

OBJECTIVE: Stimulants are first-line pharmacotherapy for individuals with attention-deficit hyperactivity disorder. However, disparities in drug coverage may contribute to inequitable treatment access. In January 2018, the government of Ontario, Canada, implemented a publicly-funded program (OHIP+) providing universal access to medications at no cost to children and youth between the ages of 0 and 24. In April 2019, the program was amended to cover only children and youth without private insurance. We studied whether these policy changes were associated with changes in prescription stimulant dispensing to Ontario children and youth. METHODS: We conducted a population-based observational natural experiment study of stimulant dispensing to children and youth in Ontario between January 2013 and March 2020. We used interventional autoregressive integrated moving average models to estimate the association between OHIP+ and its subsequent modification with stimulant dispensing trends. RESULTS: The implementation of OHIP+ was associated with a significant immediate increase in the monthly rate of stimulant dispensing of 53.6 individuals per 100,000 population (95% confidence interval [CI], 36.8 to 70.5 per 100,000) and a 14.2% (95% CI, 12.8% to 15.6%) relative percent increase in stimulant dispensing rates between December 2017 and March 2019 (1198.6 vs. 1368.7 per 100,000 population). The April 2019 OHIP+ program amendment was associated with an increase in monthly stimulant dispensing trends of 10.2 individuals per 100,000 population (95% CI, 5.0 to 15.5), with rates increasing 7.5% (95% CI, 6.2% to 8.7%) between March 2019 and March 2020 (1368.7 vs. 1470.8 per 100,000 population). These associations were most pronounced among males, children and youth living in the highest income neighbourhoods and individuals aged 20 to 24. CONCLUSION: A publicly-funded pharmacare program was associated with more children and youth being dispensed stimulants.