Deborah Randall

Opioid agonist pharmacotherapy in New South Wales from 1985 to 2006 : patient characteristics and patterns and predictors of treatment retention

AIMS The aims of this study were to: examine the number and characteristics of patients entering and re-entering opioid replacement treatment between 1985 and 2006, to examine select demographic and treatment correlates of leaving treatment between 1985 and 2000, and to compare retention rates in methadone and buprenorphine maintenance treatment from 2001 to 2006. DESIGN A retrospective cohort study using register data from the Pharmaceutical Drugs of Addiction System. SETTING Opioid substitution treatment in New South Wales (NSW), Australia. PARTICIPANTS A total of n = 42 690 individuals prescribed opioid replacement treatment between 1985 and 2006 in NSW. MEASUREMENTS Client characteristics over time, retention in days in first treatment episode, number of episodes of treatment and proportion switching medication. FINDINGS Overall, younger individuals were significantly more likely to leave their first treatment episode than older individuals. In 2001-06, after controlling for age, sex and first administration point, the hazard of leaving treatment was 1.9 times for those on buprenorphine relative to those on methadone. Retention in treatment varied somewhat across historical time, with those entering during 1995-2000 more likely to leave at an earlier stage than those who entered before that time. CONCLUSIONS Retention in treatment appears to fluctuate in inverse proportion to the availability of heroin. Individuals in contemporary treatment are older users with a lengthy treatment history. This study has provided population-level evidence to suggest that retention in methadone and buprenorphine differ in routine clinical practice. Future work might investigate ways in which patient adherence and retention may be improved.

Causes of death in a cohort treated for opioid dependence between 1985 and 2005

AIMS To examine changes in causes of death in a cohort treated for opioid dependence, across time and age; quantify years of potential life lost (YPLL); and identify avoidable causes of death. DESIGN People in New South Wales (NSW) who registered for opioid substitution therapy (OST), 1985-2005, were linked to a register of all deaths in Australia. SETTING NSW, Australia. MEASUREMENTS Crude mortality rates (CMRs), age-sex-standardized mortality rates (ASSRs) and standardized mortality ratios (SMRs) across time, sex and age. Years of potential life lost (YPLL) were calculated with reference to Australian life tables and by calculating years lost before the age of 65 years. FINDINGS There were 43 789 people in the cohort, with 412 216 person-years of follow-up. The proportion of the cohort aged 40+ years increased from 1% in 1985 to 39% in 2005. Accidental opioid overdoses, suicides, transport accidents and violent deaths declined with age; deaths from cardiovascular disease, liver disease and cancer increased. Among men, 89% of deaths were potentially avoidable; among women, 86% of deaths were avoidable. There were an estimated 160 555 YPLL in the cohort, an average of 44 YPLL per decedent and an average of 29 YPLL before age 65 years. CONCLUSIONS Among a cohort of opioid-dependent people in New South Wales, 1985-2005, almost nine in 10 deaths in the cohort were avoidable. There is huge scope to improve mortality among opioid-dependent people.

The increasing mortality burden of liver disease among opioid‐dependent people: cohort study

AIMS Hepatitis C (HCV) infection is highly prevalent among injection drug users (IDUs) and likely to cause significant mortality over time, but little research attention has focused upon the magnitude of this risk, particularly among ageing users. This study examined trends over time in mortality attributed to liver disease, and in particular contrasting this with other more commonly studied causes of death [acquired immune deficiency syndrome (AIDS), suicide and overdose] among an ageing cohort of heroin-dependent people in Australia. DESIGN Data linkage study of methadone treatment entrants with the National Deaths Index. SETTING  A cohort entering methadone treatment for heroin dependence in New South Wales, Australia, 1980-85. PARTICIPANTS   A total of 2489 people entering methadone treatment for heroin dependence and 54,847 person-years (PY) of follow-up. MEASUREMENTS   Linkage of data on all methadone entrants between 1980 and 1985 with data from the Australian National Deaths Index, linked using probabilistic record linkage software. FINDINGS There were 8.2 deaths per 1000 PY [95% confidence interval (CI) 7.5-9.0], with standardized mortality ratios (SMRs) of 4.6 (95% CI 4.2-5.0). Almost one in five (17%) of deaths were from underlying liver-related causes, most commonly viral hepatitis. The overall mortality rate for any liver cause was 1.4 deaths per 1000 PY (95% CI 1.1-1.7), 17 times higher than to the general population (95% CI 13.4-21.3), with relative elevations more marked for females (SMR 27.9; 95% CI 17.7-41.9) than males (SMR 14.5; 95% CI 10.8-19.0). Liver mortality increased over time, becoming the most common cause of death by the end of follow-up. CONCLUSIONS   Liver disease has become the most common cause of mortality among ageing opioid-dependent people in an ageing Australian cohort. There is an imperative to reduce the long-term risks of HCV and other risks to the liver, including alcohol consumption, which are typically not the major clinical focus for this group.

Increasing cancer mortality among opioid-dependent persons in Australia: a new public health challenge for a disadvantaged population

Objective: To examine cancer mortality in a population‐based cohort of opioid‐dependent persons.

Mortality risk of opioid substitution therapy with methadone versus buprenorphine: a retrospective cohort study

BACKGROUND Opioid dependence increases risk of premature mortality. Opioid substitution therapy with methadone or buprenorphine reduces mortality risk, especially for drug-related overdose. Clinical guidelines recommend methadone as the first line of opioid substitution therapy. We aimed to test whether buprenorphine treatment has a lower mortality risk than does methadone treatment by comparing all-cause mortality and drug-related overdose mortality at treatment induction, after in-treatment medication switches, and following treatment cessation. METHODS We did a retrospective cohort study of all patients with opioid dependency (n=32,033) in New South Wales, Australia, who started a methadone or buprenorphine treatment episode from Aug 1, 2001, to Dec 31, 2010, including 190,232·6 person-years of follow-up. We compared crude mortality rates (CMRs) for all-cause and drug-related overdose mortality, and mortality rate ratios (MRRs) according to age, sex, period in or out of treatment, medication type, and in-treatment switching. FINDINGS Patients who initiated with buprenorphine had reduced all-cause and drug-related mortality during the first 4 weeks of treatment compared with those who initiated with methadone (adjusted all-cause MRR 2·17, 95% CI 1·29-3·67; adjusted drug-related MRR 4·88, 1·73-13·69). For the remaining time on treatment, drug-related mortality risk did not differ (adjusted MRR 1·18, 95% CI 0·89-1·56), but weak evidence suggested that all-cause mortality was lower for buprenorphine than methadone (1·66, 1·40-1·96). In the 4 weeks after treatment cessation, all-cause mortality did not differ, but drug-related mortality was lower for methadone (adjusted all-cause MRR 1·12, 0·79-1·59; adjusted drug-related MRR 0·50, 0·29-0·86). Patients who switched from buprenorphine to methadone during treatment had lower mortality in the first 4 weeks of methadone treatment than matched controls who received methadone only (CMR difference 7·1 per 1000 person-years, 95% CI 0·1-14·0); no mortality difference was noted for switches from buprenorphine to methadone or for switches to either medication beyond the first 4 weeks of treatment. INTERPRETATION In a setting with high risk of death in the first 4 weeks of opioid substitution therapy, buprenorphine seemed to reduce mortality in this period, but little difference between buprenorphine and methadone was noted thereafter or for in-treatment switching of medications. Cross-cohort corroboration of our findings and further assessment of the stepped treatment model is warranted. FUNDING Australian National Health & Medical Research Council.

Variation in the recording of common health conditions in routine hospital data: study using linked survey and administrative data in New South Wales, Australia

Objectives To investigate the nature and potential implications of under-reporting of morbidity information in administrative hospital data. Setting and participants Retrospective analysis of linked self-report and administrative hospital data for 32 832 participants in the large-scale cohort study (45 and Up Study), who joined the study from 2006 to 2009 and who were admitted to 313 hospitals in New South Wales, Australia, for at least an overnight stay, up to a year prior to study entry. Outcome measures Agreement between self-report and recording of six morbidities in administrative hospital data, and between-hospital variation and predictors of positive agreement between the two data sources. Results Agreement between data sources was good for diabetes (κ=0.79); moderate for smoking (κ=0.59); fair for heart disease, stroke and hypertension (κ=0.40, κ=0.30 and κ =0.24, respectively); and poor for obesity (κ=0.09), indicating that a large number of individuals with self-reported morbidities did not have a corresponding diagnosis coded in their hospital records. Significant between-hospital variation was found (ranging from 8% of unexplained variation for diabetes to 22% for heart disease), with higher agreement in public and large hospitals, and hospitals with greater depth of coding. Conclusions The recording of six common health conditions in administrative hospital data is highly variable, and for some conditions, very poor. To support more valid performance comparisons, it is important to stratify or control for factors that predict the completeness of recording, including hospital depth of coding and hospital type (public/private), and to increase efforts to standardise recording across hospitals. Studies using these conditions for risk adjustment should also be cautious of their use in smaller hospitals.

Disparities in Revascularization Rates After Acute Myocardial Infarction Between Aboriginal and Non-Aboriginal People in Australia

Background— This study examined revascularization rates after acute myocardial infarction (AMI) for Aboriginal and non-Aboriginal patients sequentially controlling for admitting hospital and risk factors. Methods and Results— Hospital data from the state of New South Wales, Australia (July 2000 through December 2008) were linked to mortality data (July 2000 through December 2009). The study sample were all people aged 25 to 84years admitted to public hospitals with a diagnosis of AMI (n=59 282). Single level and multilevel Cox regression was used to estimate rates of revascularization within 30 days of admission. A third (32.9%) of Aboriginal AMI patients had a revascularization within 30 days compared with 39.7% non-Aboriginal patients. Aboriginal patients had a revascularization rate 37% lower than non-Aboriginal patients of the same age, sex, year of admission, and AMI type (adjusted hazard ratio, 0.63; 95% confidence interval, 0.57–0.70). Within the same hospital, however, Aboriginal patients had a revascularization rate 18% lower (adjusted hazard ratio, 0.82; 95% confidence interval, 0.74–0.91). Accounting for comorbidities, substance use and private health insurance further explained the disparity (adjusted hazard ratio, 0.96; 95% confidence interval, 0.87–1.07). Hospitals varied markedly in procedure rates, and this variation was associated with hospital size, remoteness, and catheterization laboratory facilities. Conclusions— Aboriginal Australians were less likely to have revascularization procedures after AMI than non-Aboriginal Australians, and this was largely explained by lower revascularization rates at the hospital of first admission for all patients admitted to smaller regional and rural hospitals, a higher comorbidity burden for Aboriginal people, and to a lesser extent a lower rate of private health insurance among Aboriginal patients.

The Smoking MUMS (Maternal Use of Medications and Safety) Study: protocol for a population-based cohort study using linked administrative data

Introduction Approximately 14% of Australian women smoke during pregnancy. Although the risk of adverse outcomes is reduced by smoking cessation, less than 35% of Australian women quit smoking spontaneously during pregnancy. Evidence for the efficacy of bupropion, varenicline or nicotine replacement therapy as smoking cessation aids in the non-pregnant population suggest that pharmacotherapy for smoking cessation is worth exploring in women of childbearing age. Currently, little is known about the utilisation, effectiveness and safety of pharmacotherapies for smoking cessation during pregnancy; neither the extent to which they are used prior to pregnancy nor whether their use has changed in response to related policy reforms. The Smoking MUMS (Maternal Use of Medications and Safety) Study will explore these issues using linked person-level data for a population-based cohort of Australian mothers. Methods and analysis The cohort will be assembled by linking administrative health records for all women who gave birth in New South Wales or Western Australia since 2003 and their children, including records relating to childbirth, use of pharmaceuticals, hospital admissions, emergency department presentations and deaths. These longitudinal linked data will be used to identify utilisation of smoking cessation pharmacotherapies during and between pregnancies and to explore the associated smoking cessation rates and maternal and child health outcomes. Subgroup and temporal analyses will identify potential differences between population groups including indigenous mothers and social security recipients and track changes associated with policy reforms that have made alternative smoking cessation pharmacotherapies available. Ethics and dissemination Ethical approval has been obtained for this study. To enhance the translation of the projects findings into policy and practice, policy and clinical stakeholders will be engaged through a reference group and a policy forum will be held. Outputs from the project will include scientific papers and summary reports designed for policy audiences.

Statistical methods to enhance reporting of Aboriginal Australians in routine hospital records using data linkage affect estimates of health disparities.

Objective: To investigate under‐recording of Aboriginal people in hospital data from New South Wales (NSW), Australia, define algorithms for enhanced reporting, and examine the impact of these algorithms on estimated disparities in cardiovascular and injury outcomes.

Mortality after admission for acute myocardial infarction in Aboriginal and non-Aboriginal people in New South Wales, Australia: a multilevel data linkage study

BackgroundHeart disease is a leading cause of the gap in burden of disease between Aboriginal and non-Aboriginal Australians. Our study investigated short- and long-term mortality after admission for Aboriginal and non-Aboriginal people admitted with acute myocardial infarction (AMI) to public hospitals in New South Wales, Australia, and examined the impact of the hospital of admission on outcomes.MethodsAdmission records were linked to mortality records for 60047 patients aged 25–84 years admitted with a diagnosis of AMI between July 2001 and December 2008. Multilevel logistic regression was used to estimate adjusted odds ratios (AOR) for 30- and 365-day all-cause mortality.ResultsAboriginal patients admitted with an AMI were younger than non-Aboriginal patients, and more likely to be admitted to lower volume, remote hospitals without on-site angiography. Adjusting for age, sex, year and hospital, Aboriginal patients had a similar 30-day mortality risk to non-Aboriginal patients (AOR: 1.07; 95% CI 0.83-1.37) but a higher risk of dying within 365 days (AOR: 1.34; 95% CI 1.10-1.63). The latter difference did not persist after adjustment for comorbid conditions (AOR: 1.12; 95% CI 0.91-1.38). Patients admitted to more remote hospitals, those with lower patient volume and those without on-site angiography had increased risk of short and long-term mortality regardless of Aboriginal status.ConclusionsImproving access to larger hospitals and those with specialist cardiac facilities could improve outcomes following AMI for all patients. However, major efforts to boost primary and secondary prevention of AMI are required to reduce the mortality gap between Aboriginal and non-Aboriginal people.