Biology subjects

Sadatsafavi, M.

Publications and source records attributed to Sadatsafavi, M..

5 recordsLinked to original sources

bioRxiv2018

The costs of misdiagnosed asthma in a longitudinal study of the general population

ObjectivesA current diagnosis of asthma cannot be objectively confirmed in many patients with physician-diagnosed asthma. Estimates of resource use in overdiagnosed cases of asthma are necessary to measure the burden of overdiagnosis and evaluate strategies to reduce this burden. We assessed the difference in asthma-related healthcare resource use between patients with a confirmed asthma diagnosis and those with asthma ruled out.\n\nDesignPopulation-based prospective cohort study.\n\nSettingParticipants were recruited through random-digit dialling of both landlines and mobile phones in BC, Canada.\n\nParticipantsWe included 345 individuals [≥]12 years of age with a self-reported physician diagnosis of asthma which was confirmed by a bronchodilator reversibility or methacholine challenge test at the end of the 12-month follow-up.\n\nPrimary and secondary outcome measuresSelf-reported annual asthma-related direct healthcare costs (2017 Canadian dollars), outpatient physician visits, and medication use from the Canadian healthcare system perspective.\n\nResultsAsthma was ruled out in 86 (24.9%) participants. Average annual asthma-related direct healthcare costs for participants with confirmed asthma were $497.9 (SD $677.9), and $307.7 (SD $424.1) for participants with asthma ruled out. In the adjusted analyses, a confirmed diagnosis was associated with higher direct healthcare costs (Relative Ratio [RR]=1.60, 95%CI 1.14-2.22), increased rate of specialist visits (RR=2.41, 95%CI 1.05-5.40) and reliever medication use (RR=1.62, 95%CI 1.09-2.35), but not primary care physician visits (p=0.10) or controller medication use (p=0.11).\n\nConclusionsA quarter of individuals with a physician diagnosis of asthma did not have asthma after objective re-evaluation. These participants still consumed a significant amount of asthma-related healthcare resources. The population-level economic burden of asthma overdiagnosis could be substantial.\n\nStrengths and limitations of this studyO_LIParticipants were recruited through random sampling of the general population in the province of British Columbia.\nC_LIO_LIAsthma diagnosis was confirmed or ruled out using sequential guideline-recommended objective airway tests.\nC_LIO_LIHealthcare resource use was self-reported, potential recall bias may have led to reduced accuracy.\nC_LIO_LIThe study was unable to evaluate the indirect costs of overdiagnosis or the cost-savings from correcting the diagnosis.\nC_LIO_LIThe generalizability of the results may be limited by regional differences in medical costs and practices.\nC_LI

epidemiology↗

bioRxiv2018

Heterogeneity in the respiratory symptoms of patients with mild-moderate COPD

BackgroundThe burden of symptoms varies markedly between patients with Chronic Obstructive Pulmonary Disease (COPD) and is only weakly correlated with lung function impairment. While heterogeneity in lung function decline and exacerbations have been previously studied, the extent of heterogeneity in symptoms and the factors associated with this heterogeneity are not well understood.\n\nMethodsA sample of the general Canadian population [≥]40 years with persistent airflow limitation was followed for up to 3 years. Participants reported whether they experienced chronic coughing, phlegm, wheezing, or dyspnea during visits at 18-month intervals. We used mixed-effect logistic regression models (separately for each symptom) to assess overall heterogeneity in the occurrence of symptoms between individuals, and the proportion of variation in symptom burden explained by lung function versus all other clinical characteristics of participants.\n\nResults548 participants (54% male, mean age 67 years) contributed 1,086 visits in total, and 82% of patients reported at least one symptom during follow-up. There was substantial heterogeneity in the individual-specific probabilities for the occurrence of symptoms. This heterogeneity was highest for dyspnea and lowest for phlegm (interquartile range of probabilities: 0.15-0.77 and <0.01-0.53, respectively). FEV1 explained 82% of the variation between individuals in the occurrence of phlegm, 26% for dyspnea, 3% for cough, and <0.1% for wheeze. All clinical characteristics of participants (including FEV1) explained between 86% of heterogeneity in the occurrence of phlegm to <1% for wheeze.\n\nConclusionThere is marked heterogeneity in the burden of respiratory symptoms between COPD patients. The ability of lung function and other commonly measured clinical characteristics to explain this heterogeneity differs between symptoms.

epidemiology↗

bioRxiv2018

Development and validation of the Evaluation Platform In COPD (EPIC): a population-based outcomes model of COPD for Canada

BackgroundWe report the development, validation, and implementation of an open-source population-based outcomes model of Chronic Obstructive Pulmonary Disease (COPD) for Canada.\n\nMethodsEvaluation Platform in COPD (EPIC) is a discrete event simulation model of Canadians 40 years of age or older. Three core features of EPIC are its open-population design (incorporating projections of future population growth, aging, and smoking trends), its incorporation of heterogeneity in lung function decline and burden of exacerbations, and its modeling of the natural history of COPD from inception. Multiple original data analyses, as well as values reported in the literature, were used to populate the model. Extensive face validity as well as internal and external validity evaluations were performed.\n\nResultsThe model was internally validated on demographic projections, mortality rates, lung function trajectories, COPD exacerbations, and stability of COPD prevalence over time within strata of risk factors. In external validation, it moderately overestimated rate of overall exacerbations in two independent trials, but generated consistent estimates of rate of severe exacerbations and mortality.\n\nLimitationsIn its current version, EPIC does not consider uncertainty in the evidence. Several components such as additional (e.g., environmental and occupational) risk factors, treatment, symptoms, and comorbidity will have to be added in future iterations.\n\nConclusionsEPIC is the first multi-purpose outcome- and policy-focused model of COPD for Canada. By modeling the natural history of COPD from its inception, it is capable of modeling the outcomes of decisions across the entire care pathway of COPD. Platforms of this type have the capacity to be iteratively updated to incorporate the latest evidence and to project the outcomes of many different scenarios within a consistent framework.

epidemiology↗

bioRxiv2017

Dose-dependent effects of inhaled corticosteroids on bone mineral density in postmenopausal women with asthma or COPD: A registry-based cohort study

BackgroundThe effect of long-term inhaled corticosteroid (ICS) therapy on the bone health of older adults remains unclear due to its possible impact on bone mineral density (BMD).\n\nObjectiveTo evaluate, cross-sectionally and longitudinally, the impact of ICS use on BMD in postmenopausal women with asthma or chronic obstructive pulmonary disease (COPD).\n\nMethodsWe used a population-based bone densitometry registry linked with administrative health data of the province of Manitoba, Canada (1999-2013), to identify women with diagnosed asthma or COPD. ICS use was defined as cumulative dispensed days prior to baseline BMD (cross-sectional analysis), and medication possession ratio (MPR) between two BMD measurements (longitudinal analysis). Results were adjusted for multiple covariates including the underlying respiratory diagnosis and its severity.\n\nResultsIn the cross sectional analysis, compared with non-users, women with the highest tertile of prior ICS exposure had lower baseline BMD at the femoral neck (-0.09 standard deviations [SD] below a healthy young adult, 95% CI: -0.16, -0.02) and total hip (-0.14 SD, 95% CI: -0.22, -0.05), but not at the lumbar spine. Longitudinally, the highest tertile of ICS exposure was associated with a slight decline in total hip BMD relative to non-users (-0.02 SD/year, 95% CI: -0.04, -0.01), with no significant effect at the femoral neck and lumbar spine. Middle and lower tertiles of ICS use had no significant effects.\n\nConclusionHigh exposure to ICS was associated with a small adverse effect on baseline hip BMD and total hip BMD loss in post-menopausal women with asthma or COPD.

epidemiology↗

bioRxiv2017

Characterising undiagnosed chronic obstructive pulmonary disease: a systematic review and meta-analysis

BackgroundA significant proportion of patients with chronic obstructive pulmonary disease (COPD) remain undiagnosed. Characterising these patients can increase our understanding of the hidden burden of COPD and the effectiveness of case detection interventions.\n\nMethodsWe conducted a systematic review and meta-analysis to compare patient and disease risk factors between patients with undiagnosed persistent airflow limitation and those with diagnosed COPD. We searched MEDLINE and EMBASE for observational studies of adult patients meeting accepted spirometric definitions of COPD. We extracted and pooled summary data on the proportion or mean of each risk factor among diagnosed and undiagnosed patients (unadjusted analysis), and coefficients for the adjusted association between risk factors and diagnosis status (adjusted analysis). This protocol is registered with PROSPERO (CRD42017058235).\n\nFindings2,083 records were identified through database searching and 16 articles were used in the meta-analyses. Diagnosed patients were less likely to have mild (v. moderate to very severe) COPD (odds ratio [OR] 0{middle dot}30, 95% CI 0{middle dot}24-0{middle dot}37, 6 studies) in unadjusted analysis. This association remained significant but its strength was attenuated in the adjusted analysis (OR 0{middle dot}72, 95% CI 0{middle dot}58-0{middle dot}89, 2 studies). Diagnosed patients were more likely to report respiratory symptoms such as wheezing (OR 3{middle dot}51, 95% CI 2{middle dot}19-5{middle dot}63, 3 studies) and phlegm (OR 2{middle dot}16, 95% CI 1{middle dot}38-3{middle dot}38, 3 studies), had more severe dyspnoea (modified Medical Research Council scale mean difference 0{middle dot}52, 95% CI 0{middle dot}40-0{middle dot}64, 3 studies) and slightly greater smoking history than undiagnosed patients. Patient age, sex, current smoking status, and the presence of coughing were not associated with a previous diagnosis.\n\nInterpretationPatients with undiagnosed persistent airflow limitation had less severe airflow obstruction and fewer respiratory symptoms than diagnosed patients. This indicates that there is lower disease burden among undiagnosed patients compared to those with diagnosed COPD, which may significantly delay the diagnosis of COPD.\n\nFundingCanadian Institutes of Health Research.\n\nDeclaration of interestsWe declare no competing interests.\n\nAuthor ContributionsMS, SB, and KJ formulated the study idea and designed the study. KJ and SG performed all data analyses and MS, SB and DS contributed to interpretation of findings. KJ wrote the first draft of the manuscript. All authors critically commented on the manuscript and approved the final version. MS is the guarantor of the manuscript.

epidemiology↗