Medicine (RMH) - Research Publications
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ItemIncreased 30-day and 1-year mortality rates and lower coronary revascularisation rates following acute myocardial infarction in patients with autoimmune rheumatic disease(BMC, 2015-02-27)INTRODUCTION: It is now well-recognised that patients with autoimmune rheumatic disease (AIRD) have a predisposition to cardiovascular disease that results in increased morbidity and mortality. Following myocardial infarction (MI), patients with rheumatoid arthritis have been shown to have an increased case fatality rate; however, this has not been demonstrated in other forms of AIRD. The aim of this study was to compare case fatality rates following a first MI in patients with AIRD versus the general population. The secondary aim was to compare revascularisation treatment following MI in patients with AIRD versus the general population. METHODS: A retrospective cohort study using two population-based linked databases was undertaken. Cases of first MI from July 2001 to June 2007 were identified based on International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification, codes. Thirty-day and one-year mortality rates were calculated (all-cause and cardiovascular causes of death). Logistic regression models were fitted to calculate the odds of mortality by AIRD status with adjustment for relevant characteristics. RESULTS: There were 79,390 individuals with a first MI, of whom 1,409 (1.8%) had AIRD. After adjusting for relevant covariates, the odds ratio (OR) for 30-day cardiovascular mortality in patients with AIRD was 1.44 (95% confidence interval (CI): 1.25 to 1.66), and the OR for 12-month cardiovascular mortality was 1.71 (95% CI: 1.51 to 1.94). The 90-day adjusted odds of percutaneous transluminal coronary angioplasty and coronary artery bypass graft were significantly lower in the AIRD group compared with controls (OR: 0.81, 95% CI: 0.70 to 0.94, and OR: 0.52, 95% CI: 0.39 to 0.69, respectively). CONCLUSIONS: We identified a higher risk-adjusted mortality rate for the majority of patients with AIRD at 30 days and 12 months after first MI. We also identified lower post-MI revascularisation rates in the AIRD group, suggesting there may be current gaps in cardiovascular treatment for patients with AIRD.
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ItemStatin initiation and treatment non-adherence following a first acute myocardial infarction in patients with inflammatory rheumatic disease versus the general population(BIOMED CENTRAL LTD, 2014)INTRODUCTION: To compare statin initiation and treatment non-adherence following a first acute myocardial infarction (MI) in patients with inflammatory rheumatic disease (IRD) and the general population. METHODS: We conducted a retrospective cohort study using a population-based linked database. Cases of first MI from July 2001 to June 2009 were identified based on International Classification of Diseases (ICD-10-AM) codes. Statin initiation and adherence was identified based on pharmaceutical claims records. Logistic regression was used to assess the odds of statin initiation by IRD status. Non-adherence was assessed as the time to first treatment gap using a Cox proportional hazards model. RESULTS: There were 18,518 individuals with an index MI over the time period surviving longer than 30 days, of whom 415 (2.2%) were IRD patients. The adjusted odds of receiving a statin by IRD status was significantly lower (OR =0.69, 95% CI: 0.55 to 0.86) compared to the general population. No association between IRD status and statin non-adherence was identified (hazard ratio (HR) =1.12, 95% CI: 0.82 to 1.52). CONCLUSIONS: Statin initiation was significantly lower for people with IRD conditions compared to the general population. Once initiated on statins, the proportion of IRD patients who adhered to treatment was similar to the general population. Given the burden of cardiovascular disease and excess mortality in IRD patients, encouraging the use of evidence-based therapies is critical for ensuring the best outcomes in this high risk group.
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ItemThe projected burden of primary total knee and hip replacement for osteoarthritis in Australia to the year 2030(BMC, 2019-02-23)BACKGROUND: Comprehensive national joint replacement registries with well-validated data offer unique opportunities for examining the potential future burden of hip and knee osteoarthritis (OA) at a population level. This study aimed to forecast the burden of primary total knee (TKR) and hip replacements (THR) performed for OA in Australia to the year 2030, and to model the impact of contrasting obesity scenarios on TKR burden. METHODS: De-identified TKR and THR data for 2003-2013 were obtained from the Australian Orthopaedic Association National Joint Replacement Registry. Population projections and obesity trends were obtained from the Australian Bureau of Statistics, with public and private hospital costs sourced from the National Hospital Cost Data Collection. Procedure rates were projected according to two scenarios: (1) constant rate of surgery from 2013 onwards; and (2) continued growth in surgery rates based on 2003-2013 growth. Sensitivity analyses were used to estimate future TKR burden if: (1) obesity rates continued to increase linearly; or (2) 1-5% of the overweight or obese population attained a normal body mass index. RESULTS: Based on recent growth, the incidence of TKR and THR for OA is estimated to rise by 276% and 208%, respectively, by 2030. The total cost to the healthcare system would be $AUD5.32 billion, of which $AUD3.54 billion relates to the private sector. Projected growth in obesity rates would result in 24,707 additional TKRs totalling $AUD521 million. A population-level reduction in obesity could result in up to 8062 fewer procedures and cost savings of up to $AUD170 million. CONCLUSIONS: If surgery trends for OA continue, Australia faces an unsustainable joint replacement burden by 2030, with significant healthcare budget and health workforce implications. Strategies to reduce national obesity could produce important TKR savings.
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ItemPerformance of the Assessment of Quality of Life Measure in People With Hip and Knee Joint Disease and Implications for Research and Clinical Use(WILEY, 2014-03)OBJECTIVE: To comprehensively evaluate the performance of the Assessment of Quality of Life (AQoL) instrument for measuring health-related quality of life (HRQOL) in people with hip and knee joint disease (arthritis or osteoarthritis). METHODS: Data from 237 individuals were available for analysis from a national cross-sectional, population-based study of hip and knee joint disease in Australia. AQoL-4D data were evaluated using Rasch analysis. A range of measurement properties was explored, including model and item fit, threshold ordering, differential item functioning, and targeting. RESULTS: Good overall fit of the AQoL with the Rasch model was demonstrated across a range of tests, supporting internal validity. Only 1 item (relating to hearing) showed evidence of misfit. Most AQoL items showed logical sequencing of response option categories, with threshold disordering evident for only 2 of the 12 items (items 4 and 9). Minor issues with potential clinical and research implications include limited options for reporting pain and some evidence of measurement bias between demographic subgroups (including age and sex). Participants' HRQOL was generally better than that represented by the AQoL items (mean ± SD for person abilities -2.15 ± 1.39, mean ± SD for item difficulties 0.00 ± 0.67), indicating ceiling effects that could impact the instrument's ability to detect HRQOL improvement in population-based studies. CONCLUSION: The AQoL is a competent tool for assessing HRQOL in people with hip and knee joint disease, although researchers and clinicians should consider the caveats identified when selecting appropriate HRQOL measures for future outcome assessment involving this patient group.
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ItemUsing WOMAC Index scores and personal characteristics to estimate Assessment of Quality of Life utility scores in people with hip and knee joint disease(SPRINGER, 2014-10)PURPOSE: To determine whether Assessment of Quality of Life (AQoL) utility scores can be reliably estimated from Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in people with hip and knee joint disease (arthritis or osteoarthritis). METHODS: WOMAC and AQoL data were analysed from 219 people recruited for a national population-based study. Generalised linear models were used to estimate AQoL utility scores based on WOMAC total and subscale scores and personal characteristics. Goodness of fit was assessed for each model, and plots of prediction errors versus actual AQoL utility scores were used to gauge bias. RESULTS: Each model closely predicted the average AQoL utility score for the overall sample (actual mean AQoL 0.64, range of predicted means 0.63-0.64; actual median AQoL 0.71, range of predicted medians 0.68-0.69). No clear preferred model was identified, and overall, the models predicted 40-46% of the variance in AQoL utility scores. The WOMAC function subscale model performed similarly to the total score model. The models functioned best at the mid-range of AQoL scores, with greater bias observed for extreme scores. Inaccuracies in individual-level estimates and low/high health-related quality of life (HRQoL) subgroup estimates were evident. CONCLUSION: Reliable overall group-level estimates were produced, supporting the application of these techniques at a population level. Using WOMAC scores to predict individual AQoL utility scores is not recommended, and the models may produce inaccurate estimates in studies targeting patients with low/high HRQoL. Where pain and stiffness data are unavailable, the WOMAC function subscale can be used to generate a reasonable utility estimate.