Validation of case-ascertainment algorithms using health administrative data to identify people who inject drugs in Ontario, Canada.

OBJECTIVE: Health administrative data can be used to improve the health of people who inject drugs by informing public health surveillance and program planning, monitoring, and evaluation. However, methodological gaps in the use of these data persist due to challenges in accurately identifying injection drug use at the population level. In this study, we validated case-ascertainment algorithms for identifying people who inject drugs using health administrative data in Ontario, Canada. STUDY DESIGN AND SETTING: Data from cohorts of people with recent (past 12 month) injection drug use, including those participating in community-based research studies or seeking drug treatment were linked to health administrative data in Ontario from 1992-2020. We assessed the validity of algorithms to identify injection drug use over varying lookback periods (i.e., all years of data [1992 onwards] or within the past 1-5 years), including inpatient and outpatient physician billing claims for drug use, emergency department visits or hospitalizations for drug use or injection-related infections, and opioid agonist treatment (OAT). RESULTS: Algorithms were validated using data from 15,241 people with recent IDU (918 in community cohorts, 14,323 seeking drug treatment). An algorithm consisting of ≥1 physician visit, emergency department visit or hospitalization for drug use, or OAT record could effectively identify IDU history (91.6% sensitivity, 94.2% specificity) and recent IDU (using 3 years lookback: 80.4% sensitivity, 99% specificity) among community cohorts. Algorithms were generally more sensitive among people who inject drugs seeking drug treatment. CONCLUSION: Validated algorithms using health administrative data performed well in identifying people who inject drugs. Despite high sensitivity and specificity, the positive predictive value of these algorithms will vary depending on the underlying prevalence of injection drug use in the population in which they are applied.

Health utilities in adults with hemophilia A: A retrospective cohort study.

INTRODUCTION: Haemophilia A negatively affects a patient's quality of life. There is a limited amount of health utility data (a measure of health-related quality of life) available for patients with haemophilia A. This information is crucial for cost-effectiveness analysis for haemophilia A treatment. OBJECTIVES: The goal of this project is to elicit the health utilities and factors impacting utility values for haemophilia A patients in Canada. METHODS: This is a population-based, cross-sectional, retrospective study of health utilities in patients with haemophilia A using Patient Report Outcomes Burdens and Experiences (PROBE) components from the Canadian Bleeding Disorders Registry (CBDR). A review of the mean utilities for three severity states, defined by clotting factor VIII level, was completed. A multiple linear regression analysis was completed to examine the determinants of health utilities including age, treatment type, chronic pain status, number of limited joints, and bleed rate. RESULTS: The average utility values (and standard deviations) for patients with haemophilia A in Canada are .79(.17), .76(.20), and .77(.19) for patients with severe, moderate, and mild haemophilia. The regression showed chronic pain status and the number of additional comorbidities as major significant factors (p-value < .001) in haemophilia A utility. Haemophilia severity was shown to be a major factor with smaller p-value (p-value < .05). CONCLUSIONS: Haemophilia A patients have lower utility than the general population. Chronic pain was shown to be a significant, major factor in health-related quality of life. Our study is essential for valuing health outcomes in haemophilia A-related cost-effectiveness analysis.

Disparities in health utilities among hepatitis C patients receiving care in different settings.

BACKGROUND: Although chronic hepatitis C (CHC) disproportionately affects marginalized individuals, most health utility studies are conducted in hospital settings which are difficult for marginalized patients to access. We compared health utilities in CHC patients receiving care at hospital-based clinics and socio-economically marginalized CHC patients receiving care through a community-based program. METHODS: We recruited CHC patients from hospital-based clinics at the University Health Network and community-based sites of the Toronto Community Hep C Program, which provides treatment, support, and education to patients who have difficulty accessing mainstream health care. We elicited utilities using six standardized instruments (EuroQol-5D-3L [EQ-5D], Health Utilities Index Mark 2/Mark 3 [HUI2/HUI3], Short Form-6D [SF-6D], time trade-off [TTO], and Visual Analogue Scale [VAS]). Multivariable regression analysis was performed to examine factors associated with differences in health utility. RESULTS: Compared with patients recruited from the hospital setting (n = 190), patients recruited from the community setting (n = 101) had higher unemployment (87% versus 67%), history of injection drug use (88% versus 42%), and history of mental health issue(s) (79% versus 46%). Unadjusted health utilities were lower in community than hospital patients (e.g., EQ-5D: 0.722 [SD 0.209] versus 0.806 [SD 0.195]). Unemployment and a history of mental health issue(s) were significant predictors of low health utility. CONCLUSIONS: Socio-economically marginalized CHC patients have lower health utilities than patients typically represented in the CHC utility literature. Their utilities should be incorporated into future cost-utility analyses to better represent the population living with CHC in health policy decisions.

Estimation of COVID-19 Period Prevalence and the Undiagnosed Population in Canadian Provinces: Model-Based Analysis.

BACKGROUND: The development of a successful COVID-19 control strategy requires a thorough understanding of the trends in geographic and demographic distributions of disease burden. In terms of the estimation of the population prevalence, this includes the crucial process of unravelling the number of patients who remain undiagnosed. OBJECTIVE: This study estimates the period prevalence of COVID-19 between March 1, 2020, and November 30, 2020, and the proportion of the infected population that remained undiagnosed in the Canadian provinces of Quebec, Ontario, Alberta, and British Columbia. METHODS: A model-based mathematical framework based on a disease progression and transmission model was developed to estimate the historical prevalence of COVID-19 using provincial-level statistics reporting seroprevalence, diagnoses, and deaths resulting from COVID-19. The framework was applied to three different age cohorts (< 30; 30-69; and ≥70 years) in each of the provinces studied. RESULTS: The estimates of COVID-19 period prevalence between March 1, 2020, and November 30, 2020, were 4.73% (95% CI 4.42%-4.99%) for Quebec, 2.88% (95% CI 2.75%-3.02%) for Ontario, 3.27% (95% CI 2.72%-3.70%) for Alberta, and 2.95% (95% CI 2.77%-3.15%) for British Columbia. Among the cohorts considered in this study, the estimated total number of infections ranged from 2-fold the number of diagnoses (among Quebecers, aged ≥70 years: 26,476/53,549, 49.44%) to 6-fold the number of diagnoses (among British Columbians aged ≥70 years: 3108/18,147, 17.12%). CONCLUSIONS: Our estimates indicate that a high proportion of the population infected between March 1 and November 30, 2020, remained undiagnosed. Knowledge of COVID-19 period prevalence and the undiagnosed population can provide vital evidence that policy makers can consider when planning COVID-19 control interventions and vaccination programs.

Cost-effectiveness of obeticholic acid for the treatment of non-alcoholic steatohepatitis: An early economic evaluation.

BACKGROUND: Currently, there are no pharmacological options available for the treatment of non-alcoholic steatohepatitis (NASH). In the 18-month interim analysis of an ongoing randomized, placebo-controlled phase 3 trial (REGENERATE), early results demonstrated that obeticholic acid (OCA) 25 mg significantly improved fibrosis with no worsening of NASH among patients with NASH and fibrosis compared with placebo (PBO). This study aimed to assess the potential cost-effectiveness of OCA compared with PBO in NASH patients. METHODS: A state-transition model was developed to perform a cost-utility analysis comparing two treatment strategies, PBO and OCA 25 mg, from a Canadian public payer perspective. The model time horizon was lifetime with annual cycle lengths. Cost and utility parameters were discounted at 1.5% annually. The efficacy data were obtained from the REGENERATE trial, and costs and utilities were derived from other published literature. Probabilistic and deterministic sensitivity analyses were performed to test the robustness of the model. RESULTS: Treatment with OCA led to reductions of 3.58% in decompensated cirrhosis cases, 3.95% in hepatocellular carcinoma, 7.88% in liver transplant, and 6.01% in liver-related death. However, at an annual price of CAD $36,000, OCA failed to be cost-effective compared with PBO at an incremental cost-effectiveness ratio of $815,514 per quality-adjusted life year (QALY). An 88% reduction in drug price to an annual cost of $4,300 would make OCA cost-effective at a willingness-to-pay threshold of $50,000/QALY. CONCLUSIONS: OCA failed to be cost-effective compared with PBO, despite demonstrating clinical benefits due to a high drug cost. A significant price reduction would be needed to make the drug cost-effective.

Economic evaluation of compression stockings for the prevention of venous leg ulcer recurrence in Ontario.

OBJECTIVE: Approximately between 1.5 and 3.0 per 1000 people are affected by venous leg ulcers (VLUs). The treatment and management of VLUs is costly and recurrence is a major concern. There is evidence that compression stockings can reduce the rate of re-ulceration compared with no compression. We present the first cost-effective analysis of compression stockings in preventing recurrence of VLUs from the perspective of the Ontario healthcare system. METHOD: A cost-utility analysis with a five-year time horizon was conducted. Use of compression stockings was compared with usual care (no compression stockings). We simulated a hypothetical cohort of 65-year-old patients with healed VLUs, using a state-transition model. Model input parameters were obtained mainly from the published literature. We estimated quality-adjusted life years (QALYs) gained and direct medical costs. We conducted various sensitivity analyses. RESULTS: Compared with usual care, compression stockings were associated with higher costs and increased QALYs. Cost-utility analysis showed that the incremental cost-effectiveness ratio of compression stockings was $23,864 per QALY gained compared with no compression stockings. The most influential drivers of cost-effectiveness were the utility value of healed VLUs, cost of stockings, number of stocking replacements, monthly prevention cost and the risk of VLU recurrence. CONCLUSION: Compared with usual care, compression stockings were cost-effective in preventing VLUs, using a willingness-to-pay threshold of $50,000. These observations were consistent even when uncertainty in model inputs and parameters were considered.

Long-term morbidity and mortality in a Canadian post-transfusion hepatitis C cohort: Over 15 years of follow-up.

The Federal Government of Canada established a $1.1 billion compensation programme in 1999 to support individuals who acquired hepatitis C virus (HCV) through blood products between January 1986 and July 1990. We aimed to describe the morbidity and mortality of this unique post-transfusion cohort (n = 4550) followed for over 15 years from 2000 to 2016. The age-standardized mortality rates were compared with that of the Canadian general population and HCV cohorts from other countries. We evaluated all-cause mortality using Kaplan-Meier survival curves and HCV-related and unrelated mortality using competing risk models. The age-standardized all-cause and HCV-related mortality rates per 10 000 person-years were 127 (95% CI: 117-138) and 76 (95% CI: 69-85) for males, and 77 (95% CI: 69-87) and 43 (95% CI: 37-51) for females, respectively. The risk of death of the post-transfusion cohort was almost twice as high as the Canadian general population (rate ratio = 1.8; 95% CI: 1.7-1.9). All-cause, HCV-related and HCV-unrelated mortality were 20%, 12% and 8%, respectively at 15 years of follow-up. By comparison, HCV-related mortality rates per 10 000 person-years for population-based HCV cohorts varied from 18 and 11 in Australia to 65 and 43 in Scotland for males and females, respectively. We reported long-term follow-up data for the largest post-transfusion cohort in the literature. The all-cause mortality rates were markedly higher than that of the Canadian general population. We also showed that HCV-related mortality were greater compared to other HCV cohorts. This suggests that continued efforts to identify and treat post-transfusion HCV are warranted.

Strategies to achieve population control of HCV infection: results of a multidisciplinary focus group.

Background: To meet the World Health Organization's ambitious target to eradicate hepatitis C virus (HCV) by 2030, a comprehensive strategy is needed in Canada to ensure everyone infected with HCV is identified, diagnosed, and treated. The purpose of this study was to highlight the barriers to any strategy aimed at achieving this goal. Methods: A focus group was formed (N = 11) that consisted of clinicians, patients, drug program budget managers, industry representatives, and individuals from provincial public health and federal agencies in Canada. The group met in person for a half-day focus group session. Two discussions were held: one on future barriers related to HCV treatment and one related to HCV screening. A grounded theory approach was used to elicit key themes from the day's discussion. Results: Nine themes were identified. Four themes related to HCV screening: public awareness and engagement, resource infrastructure and capacity, heterogeneity between provinces, and mechanisms of screening. Three themes related to HCV treatment: access to treatment and illicit drug use, linkage to care, and predicting post-treatment outcomes. Two overarching themes that contributed to most discussions were a focus on baby boomers versus persons who inject drugs and the need for further education and training. Conclusion: The views and findings extracted from this qualitative research complement proposals of national strategies from organizations such as the Canadian Network on Hepatitis C. This work highlights the financial, logistical, and ethical constraints that need to be tackled to make HCV elimination proposals a reality.

Can we afford not to screen and treat hepatitis C virus infection in Canada?

Background: Screening for hepatitis C virus (HCV) followed by direct-acting antiviral (DAA) treatment in individuals born between 1945 and 1964 has been shown to be both effective and cost-effective, but the question of affordability remains unresolved. We looked at long-term cost and health outcomes of HCV screening for Ontario up to 2030. Methods: We used a validated state-transition model to analyze the budget and health impact of HCV screening followed by DAA treatment in individuals born between 1945 and 1964 versus current practice. We used a payer's perspective, discounting costs at an annual rate of 1.5%. Costs, liver-related deaths, and hepatocellular carcinoma (HCC) and decompensated cirrhosis (DC) cases detected were measured over a 14-year period. Results: By 2030, the cost of implementing a HCV screening program for individuals born between 1945 and 1964 will add an additional $845 million to the Ontario health care budget. Sensitivity analyses showed that DAA costs had the largest effect on the budget, and decreasing DAA costs to $16,000 will lead to a significantly lower budget impact of $331 million. Regarding population health, a screen-and-treat strategy will prevent 1,199 cases of HCC, 1,565 cases of DC, and 1,665 liver-related deaths by 2030. Conclusions: Contrasting the budget impact of this HCV screening strategy with other recommended health services and technologies, we conclude that HCV screening should be considered affordable. If Canada is committed to meeting the targets set out by the World Health Organization, then provinces cannot afford to not expand current screening programs.

A constructive approach for discovering new drug leads: Using a kernel methodology for the inverse-QSAR problem.

BACKGROUND: The inverse-QSAR problem seeks to find a new molecular descriptor from which one can recover the structure of a molecule that possess a desired activity or property. Surprisingly, there are very few papers providing solutions to this problem. It is a difficult problem because the molecular descriptors involved with the inverse-QSAR algorithm must adequately address the forward QSAR problem for a given biological activity if the subsequent recovery phase is to be meaningful. In addition, one should be able to construct a feasible molecule from such a descriptor. The difficulty of recovering the molecule from its descriptor is the major limitation of most inverse-QSAR methods. RESULTS: In this paper, we describe the reversibility of our previously reported descriptor, the vector space model molecular descriptor (VSMMD) based on a vector space model that is suitable for kernel studies in QSAR modeling. Our inverse-QSAR approach can be described using five steps: (1) generate the VSMMD for the compounds in the training set; (2) map the VSMMD in the input space to the kernel feature space using an appropriate kernel function; (3) design or generate a new point in the kernel feature space using a kernel feature space algorithm; (4) map the feature space point back to the input space of descriptors using a pre-image approximation algorithm; (5) build the molecular structure template using our VSMMD molecule recovery algorithm. CONCLUSION: The empirical results reported in this paper show that our strategy of using kernel methodology for an inverse-Quantitative Structure-Activity Relationship is sufficiently powerful to find a meaningful solution for practical problems.