Biology subjects

FitzGerald, J. M.

Publications and source records attributed to FitzGerald, J. M..

3 recordsLinked to original sources

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↗