The accuracy of administrative health data for identifying patients with rheumatoid arthritis: a retrospective validation study using medical records in Western Australia

Validated administrative data based ICD-10 algorithms for chronic conditions: A systematic review

OBJECTIVE

This systematic review aimed to identify ICD-10 based validated algorithms for chronic conditions using health administrative data.

METHODS

A comprehensive systematic literature search using Ovid MEDLINE, Embase, PsycINFO, Web of Science and CINAHL was performed to identify studies, published between 1983 and May 2023, on validated algorithms for chronic conditions using administrative health data. Two reviewers independently screened titles and abstracts and reviewed full text of selected studies to complete data extraction. A third reviewer resolved conflicts arising at the screening or study selection stages. The primary outcome was validated studies of ICD-10 based algorithms with both sensitivity and PPV of ≥70 %. Studies with either sensitivity or PPV <70 % were included as secondary outcomes.

RESULTS

Overall, the search identified 1686 studies of which 54 met the inclusion criteria. Combining a previously published literature search, a total of 61 studies were included for data extraction. The study identified 40 chronic conditions with high validity and 22 conditions with moderate validity. The validated algorithms were based on administrative data from different countries including Canada, USA, Australia, Japan, France, South Korea, and Taiwan. The algorithms identified included several types of cancers, cardiovascular conditions, kidney diseases, gastrointestinal disorders, and peripheral vascular diseases, amongst others.

CONCLUSION

With ICD-10 prominently used across the world, this up-to-date systematic review can prove to be a helpful resource for research and surveillance initiatives using administrative health data for identifying chronic conditions.

A novel method to monitor rheumatoid arthritis prevalence using hospital and medication databases

BACKGROUND

Most estimates of rheumatoid arthritis (RA) prevalence, including all official figures in Australia and many other countries, are based on self-report. Self-report has been shown to overestimate RA, but the 'gold standard' of reviewing individual medical records is costly, time-consuming and impractical for large-scale research and population monitoring. This study provides an algorithm to estimate RA cases using administrative data that can be adjusted for use in multiple contexts to provide the first approximate RA cohort in Australia that does not rely on self-report.

METHODS

Survey data on self-reported RA and medications from 25 467 respondents of the Australian Longitudinal Study on Women's Health (ALSWH) were linked with data from the national medication reimbursement database, hospital and emergency department (ED) episodes, and Medicare Benefits codes. RA prevalence was calculated for self-reported RA, self-reported RA medications, dispensed RA medications, and hospital/ED RA presentations. Linked data were used to exclude individuals with confounding autoimmune conditions.

RESULTS

Of 25 467 survey respondents, 1367 (5·4%) women self-reported disease. Of the 26 840 women with hospital or ED presentations, 292 (1·1%) received ICD-10 codes for RA. There were 1038 (2·8%) cases by the medication database definition, and 294 cases (1·5%) by the self-reported medication definition. After excluding individuals with other rheumatic conditions, prevalence was 3·9% for self-reported RA, 1·9% based on the medication database definition and 0·5% by self-reported medication definition. This confirms the overestimation of RA based on self-reporting.

CONCLUSIONS

We provide an algorithm for identifying individuals with RA, which could be used for population studies and monitoring RA in Australia and, with adjustments, internationally. Its balance of accuracy and practicality will be useful for health service planning using relatively easily accessible input data.

Population-wide long-term study of incidence, renal failure, and mortality rates for lupus nephritis

OBJECTIVE

Given limited regional data, we investigate the state-wide epidemiology, renal and patient outcomes for lupus nephritis (LN) in Western Australia (WA).

METHODS

Patients hospitalized with incident SLE (≥2 diagnostic codes in the state-wide WA Health Hospital Morbidity Data Collection) in the period 1985-2015 were included (n = 1480). LN was defined by the presence of glomerulonephritis and/or raised serum creatinine. Trends over three study decades for annual incidence rate (AIR)/100.000 population, mortality (MR), and end-stage renal disease (ESRD) rates/100 person years were analyzed by least square regression and compared with a matched control group (n = 12 840).

RESULTS

Clinical evidence of LN developed in 366 SLE patients (25.9%) after a median disease duration of 10 months (IQR 0-101) with renal biopsy performed in 308 (84.2%). The AIR for LN (0.63/100.000) did not change significantly over time (R2  = .11, p = .85), while point prevalence reached 11.9/100.000 in 2015. ESRD developed in 14.1% (n = 54) of LN patients vs. 0.2% in non-LN SLE patients and 0.05% in controls (all p ≤ 0.01). ESRD rates increased over time in LN patients (0.4 to 0.7, R2 = .52, p = .26). The odds ratio for death was 8.81 (CI 3.78-22.9) for LN and 6.62 (CI 2.76-17.9) for non-LN SLE patients compared to controls and MR for LN patients increased over time (1.3 to 2.2, R2 = .84, p = .26).

CONCLUSIONS

The incidence rate of LN in WA remained unchanged over 30 years. A lack of improvement in renal failure and mortality rates illustrates the pressing need for better long-term treatment options and/or strategies in LN.

Joint surgery rates in lupus: a long-term cohort study

AIM

With scarce data on the need and type of joint surgery in SLE, we investigated the long-term rates and underlying causes for arthroplasty, arthrodesis and synovectomy in patients with SLE.

METHODS

Procedure dates for arthroplasty, arthrodesis or synovectomy were retrieved from the state-wide Hospital Morbidity Data Collection between 1985 and 2015 for patients with SLE (n=1855) and propensity-matched controls (n=12 840). Patients with SLE with ≥two additional diagnostic codes for rheumatoid arthritis were classified as rhupus. ORs and incidence rates (IRs) per 100 person-years for joint procedures (JPs) were compared among patients with rhupus, patients with other SLE and controls across three study decades by regression analysis.

RESULTS

More patients with SLE than controls underwent a JP (11.6% vs 1.3%; OR 10.8, CI 8.86 to 13.24) with a higher IR for JP in patients with SLE (1.9 vs 0.1, rate ratio 19.9, CI 16.83 to 23.55). Among patients with SLE, patients with rhupus (n=120, 60.5%) had the highest odds of arthroplasty (OR 4.49, CI 2.87 to 6.92), arthrodesis (OR 6.64, CI 3.28 to 12.97) and synovectomy (OR 9.02,CI 4.32 to 18.23). Over time, the IR for overall JP in patients with rhupus was unchanged (8.7 to 8.6, R2=0.004, p=0.98), although the IR for avascular necrosis underlying arthroplasty decreased for all patients with SLE (0.52 to 0.10, p=0.02). Patients with other SLE also had significantly higher OR and IR for all three JPs than controls with insignificant decreases in synovectomy and increases in arthroplasty over time in this group.

CONCLUSIONS

The overall burden of joint surgery in SLE is high and despite a reduction in avascular necrosis, arthroplasty and arthrodesis rates have not decreased over time. These data indicate a need for increased efforts to prevent joint damage in patients with lupus.

Mortality Trends Among Patients with Rheumatoid Arthritis in Western Australia

INTRODUCTION

With scarce comparative data on mortality in Australian patients with rheumatoid arthritis (RA), we investigated temporal changes in standardized mortality rates for patients with RA using longitudinal linked population-wide health data in Western Australia (WA) over the period 1980 to 2015.

METHODS

The study included 17,125 patients with a first-time hospital contact for RA (ICD-10-AM M05.00-M06.99 and ICD-9-AM 714.00-714.99) in the study period. Standardized mortality rate ratios (SMRRs) for the RA cohort versus the WA general population was estimated using direct age standardization. We analyzed temporal trends over with dates and causes provided by the WA Death Registry.

RESULTS

During 356,069 patient-years of follow-up, a total of 8955 (52%) deaths occurred in the RA cohort. The SMRR was 2.24 (95% CI 2.15-2.34) in males and 3.09 (95% CI 3.00-3.19) in females over the study period. SMRR decreased since 2000 to 1.59 (95% CI 1.39-1.81) for the period 2011-2015. Median survival was 26.80 years (95% CI 26.30-27.30), where age and comorbidity independently increased the risk of death. The leading causes of deaths were cardiovascular diseases (26.60%), cancer (16.80%), rheumatic diseases (5.80%), chronic pulmonary disease 491 (5.50%), dementia (3.00%), and diabetes 235 (2.6%).

CONCLUSIONS

The mortality rate in patients with RA in WA has decreased but remains 1.59-times higher than in community counterparts, suggesting that there is room for further improvement. Comorbidity is the main modifiable risk factor to further reduce mortality in patients with RA.

The effect of TNF treatment uptake on incident hospital admission in Western Australia

OBJECTIVE

Treatment strategies for juvenile idiopathic arthritis (JIA) have shifted significantly over the last 20 years. We examined the effect of the introduction of government-subsidised TNF inhibitor (TNFi) treatment on incident hospitalisation for JIA.

METHODS

Western Australian (WA) hospital data were used to identify patients < 16 years hospitalised with JIA between 1990 and 2012. Changes in the number of patients with an incident hospitalisation, overall admissions and admissions for joint aspiration were examined using join-point regression TNFi dispensing data from 2002-2012 was used to describe defined daily doses (DDD)/1000 population/day.

RESULTS

We included 786 patients (59.2% girls, median age 8 years) with a first-time admission with JIA. The annual incident admission rate was 7.9 per 100,000 person-years (95%CI: 7.3, 8.4) which did not change significantly between 1990 and 2012 (annual percentage change (APC): 1.3, 95%CI: -0.3, 2.8). Annual hospital-based prevalence of JIA reached 0.72/1000 in 2012. DDD for TNFi usage rose steadily from 2003 indicating TNFi usage by 1/2700 children in 2012, while overall admission rates (APC 3.7; 95%CI: 2.3, 5.1) and admission rates for joint injections (APC 4.9%; 95%CI: 3.8, 6.0) also increased significantly in that period.

CONCLUSION

Incident inpatient admission rates for JIA were stable over a 22-year period. The uptake of TNFi was not associated with lower admission rates for JIA, due mainly to an increase in admissions for joint injection. These results indicate a notable but unexpected change in hospital-based management of JIA since the introduction of TNFi therapy in WA, where hospital-based prevalence of JIA is slightly higher than in North America.

The prevalence of rheumatoid arthritis in Western Australia

BACKGROUND

Rheumatoid arthritis (RA) is the most common form of autoimmune arthritis, but the prevalence in Australia is unknown. We estimated RA period prevalence and identified factors associated with frequent RA hospitalisations, using linked administrative health and state-specific Australian Pharmaceutical Benefits Scheme (PBS) datasets in Western Australia (WA) from 1995 to 2014.

METHODS

This was a longitudinal population-based cohort study using two independent datasets to identify prevalent RA patients. RA prevalence was calculated per 1000 hospital separations and biological therapy users. RA patients were identified in the WA linked health dataset using ICD codes 714.0-714.9 and M05.00-M06.99. Dispensing data on biological therapy for RA were obtained from PBS records and converted to defined daily doses /1000 population/day. Multivariable logistic regression was used to analyse factors associated with frequent RA hospitalisations (> 2/year), controlling for sex, age, and geographic locations. Potential interactions were assessed using logistic regression in a stepwise approach.

RESULTS

A total of 17,125 RA patients had 50,353 hospital separations between 1995 and 2014, averaging three hospitalisations per patient over 20 years. The RA period prevalence was 3.4 per 1000 separations (0.34%; 95% CI 0.33-0.34), while the RA period prevalence based on biological therapy use was 0.36% (95% CI 0.35-0.37). The corrected RA prevalence based on biological therapy usage was 0.36% (95% CI 0.35-0.37) for the 2005-2009 and increased to 0.72% (95% CI 0.70-0.74) in 2010-2014 period. Associated factors for frequent RA hospitalisations were being female [1.21 (95% CI 1.15-1.26)], aged 60-69 years [4.45 (95% CI 3.74-5.30)], living in rural areas [1.12 (95% CI 1.02-1.24)]. The odd ratio of interaction between these associated factors was 1.34 (95% CI 1.16-1.55).

CONCLUSION

The minimal prevalence of RA in Western Australia is 0.34-0.36%, which falls within the literature range. Older female RA patients in rural were more likely to be hospitalised, suggesting unmet primary care for needs.

Temporal trends in hospitalisation for opportunistic infections in lupus patients in Western Australia

BACKGROUND

Lupus patients often require aggressive immunosuppressive therapy, which increases the risk for infections. We studied the temporal rates for opportunistic infections (OI) and associated mortality in lupus patients hospitalised in Western Australia.

METHODS

All patients hospitalized in the period 1985-2015 with ≥2 ICD based diagnostic codes for SLE were included. OI was defined as a microbiologically confirmed mycobacterial, fungal, or viral infection. Descriptive data are given as median (IQR) and frequency (%) with incidence rates (IR) calculated per 1000 person years and IR trend rates analysed across 10-year periods by least square regression (R2).

RESULTS

The study cohort (n = 1408) contained 85.3% females with age at entry 35 years (IQR 22-51). During median follow-up of 21.1 years (IQR 17.5-29.6) hospitalisation for OI occurred in 121 (8.6%) patients with recurrent or multiple OI observed in 42 (34.7%) patients. During 29.771 thousand person years, a total of 295 OI were diagnosed for an overall IR rate of 9.91 (CI 8.82-11.09)/1000 person years which did not decrease significantly over time (R² 0.14). Significant decreases were however seen in the IR for tuberculosis (R² 0.88), cryptococcal (R² 0.98) and pneumocystis (R² 0.98) infections, with increasing IR observed for other mycobacteria (R² 0.99) and aspergillosis (R² 0.55) and little change seen for H Zoster (R² 0.18) and Varicella (R² 0.10) infections. In-hospital death during OI admission occurred in 9/121 patients (7.4%). There was no significant gender difference in IR or outcome of OI.

CONCLUSIONS

Hospitalization rates for OI in lupus patients have not changed significantly over time, but there has been a clear shift in the underlying OI. The decrease in mycobacterial and pneumocystis infections suggest successful prophylaxis but the increase in viral and mycotic infections indicate a sustained need to improve prevention of these OI in lupus patients.

Total Hip Replacement in Patients with Rheumatoid Arthritis: Trends in Incidence and Complication Rates Over 35 Years

INTRODUCTION

Advances in rheumatoid arthritis (RA) management have made disease remission achievable. We evaluated trends in total hip replacement (THR) and postoperative outcomes in patients with RA in Western Australia (WA) over more than three decades.

METHODS

This was a retrospective analysis of routinely collected prospective data from a state-wide registry containing longitudinally linked administrative health data based on International Classification of Diseases (ICD) diagnostic and procedural codes. We included patients with two or more diagnostic codes for RA (between 1980 and 2015) and studied THR incidence rates (THR IR) and complication rates (revision, peri-prosthetic fracture, infection, venous thrombosis, and mechanical loosening). Survival rates were estimated by Kaplan-Meier method and predictors analyzed by Cox regression.

RESULTS

We followed 9201 RA patients over 111,625 person-years, during which 1560 patients (16.9%) underwent THR. From 1985 to 2015, THR IR (per 1000 RA patient-years) decreased from 20.8 (95% CI 20.1-21.5) to 7.3 (95% CI 7.2-7.5), and 5-year THR-free survival increased from 84.3 to 95.3% (1980-2015). Ten-year prosthetic survival was 91.2%. Complication rates in the first 5 years post-THR decreased significantly from 13.1 to 3.7% (p < 0.001). Mechanical complications such as loosening and periprosthetic fracture rates decreased significantly (> 35%, P < 0.05), while infection and revision did not change over the observation period (p > 0.05).

CONCLUSIONS

Over the last 30 years in RA patients, THR IR and mechanical complication rates decreased significantly, but the medical complication of infection has not changed significantly.

The temporal association between hospital admissions, biological therapy usage and direct health care costs in rheumatoid arthritis patients

The Australian Pharmaceutical Benefits Scheme (PBS) has subsidised biological therapy since 2003. We investigated the association between biological therapy for RA hospitalisation rates and health-care costs.Hospital admissions for RA patients between 1995 and 2014 were identified in the Western Australia (WA) Hospital Morbidity Data Collection (ICD codes 714 and M05.00-M06.99). State-specific dispensing data for conventional and biological therapies for RA was obtained from Statistics Australia and expressed as defined daily doses/1000 population/day (DDD) using WA population census. Principal component analysis (PCA) was applied to determine the relationship between DMARDs use and hospital admission rates.A total of 17,125 patients had 50,353 admissions with a diagnostic code for RA. Between 1995 and 2002, the number of RA admissions fell from 7.9 to 2.6/1000 admissions, while conventional therapy use rose from 1.45 to 1.84 DDD. Between 2003 and 2014, RA admissions decreased further to 1.9/1000 hospital admissions, while conventional therapy use increased to 2.19 DDD and biological therapy from 0.01 to 1.0 DDD. In PCA, conventional and biological therapies use had an inverse relationship with hospital admission rates. Annual costs of biological therapy utilisation was 22.5 million in 2003-2014, while the annual cost saving of RA hospital admissions was 9.2 million.The increased use of conventional therapy use for RA has coincided with a significant decline in hospital admissions for RA patients in WA, while a more modest further decline followed biological therapy introduction. Biological therapy was not as cost-effective as conventional in relation to RA hospital admissions costs.