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L Irwig

Publications and source records attributed to L Irwig.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cost-effectiveness analysis of screening by faecal occult blood testing for colorectal cancer in Australia.

The incremental costs and effects of annual faecal occult blood test screening in Australia were modelled for a hypothetical cohort of 1000 persons offered screening or not offered screening. Incremental costs and effects were estimated as the differences in direct health care costs (Australian costs) and years of life remaining between the annual-screen group and the control (no screen) group, based on the published results of the Minnesota randomised controlled trial. The cost per life year saved was $24,660. The greatest source of variability in the cost-effectiveness ratio is the effectiveness of screening. The 95 percent confidence interval for cumulative mortality in the annual-screen group is 3.86 to 7.9 per 1000, assuming the control rate is fixed at 8.83 per 1000. With this confidence interval, the cost per life year saved ranges from $12,695 to $67,848. The cost-effectiveness ratio increases to $48,000 if no mortality benefit is assumed beyond the end of the trial follow-up period, 13 years. The results are sensitive to the cost of colonoscopy (at $400 per colonoscopy, the cost per life year saved is $12,319) and the false-positive rate. The cost-effectiveness of colorectal cancer screening is comparable with that of other screening programs but further evidence is needed on the efficacy of screening. Whether the benefits of colorectal cancer screening outweigh the harm and costs needs to be more certain before more resources are committed to mass screening. Health policy planners should initiate planning for Australian pilot projects in the event that the efficacy of screening is confirmed by two current studies.

Australia↗
PubMed1996

Attitudes and beliefs of staff working in methadone maintenance clinics.

Two attitudinal scales measuring commitment to abstinence-oriented treatment policies and disapproval of illicit drug use were derived from a survey of 90 staff working in 10 public methadone maintenance clinics in Sydney, Australia. The two scales were shown to be valid constructs by confirmatory factor analysis and to be internally reliable and to have high test-retest reliability. The factors underlying the two scales were highly correlated (r = .77), indicating support for policies that enforce abstinence and limit the duration of maintenance is highly associated with personal disapproval of drug use. There was no significant correlation between staff's knowledge of the benefits of methadone maintenance and their support for abstinence-oriented policies.

Attitude↗
PubMed1996

Physicians' attitudes and retention of patients in their methadone maintenance programs.

A study was undertaken to investigate the influence of methadone prescribers' commitment to abstinence-oriented policies on retention in their maintenance programs. Two hundred and eighty patients recently enrolled in single-person, private methadone programs were interviewed and followed for 8 years. The prescribing physicians' scores on an Abstinence Orientation Scale, derived from an independent sample of methadone program staff, were significantly associated with their patients' risk of premature discharge. The influence of program orientation on retention was greater the higher the maximum dose of methadone. More attention should be paid to the effect of staff attitudes and beliefs on the effectiveness of maintenance treatment.

Adult↗
PubMed1995

Meta-analysis of Pap test accuracy.

A literature search identified 62 studies published by August 1992 comparing Papanicolaou (Pap) test results with histology. Critical appraisal revealed that 82% of these had potential for verification bias and that only 37% stated that cytology and histology were independently assessed. Estimates of sensitivity and specificity ranged from 11 to 99% and 14 to 97%, respectively, and were highly negatively correlated (r = -0.63). Meta-analysis was used to combine data from 59 studies to estimate the accuracy of the Pap test using a summary receiver operating characteristic curve and to examine the effect of study quality. The summary receiver operating characteristic curve suggests that the Pap test may be unable to achieve concurrently high sensitivity and specificity. For example, specificity in the 90-95% range corresponds to sensitivity in the 20-35% range. Pap test accuracy was not associated with reported study characteristics or dimensions of quality. Future primary studies should pay more attention to methodologic standards for the conduct and reporting of diagnostic test evaluations.

Bias↗
PubMed1995

Meta-analytic methods for diagnostic test accuracy.

Meta-analyses of diagnostic test accuracy are uncommon and often based on separate pooling of sensitivity and specificity, which can lead to biased estimates. Recently, several appropriate methods have been developed for meta-analysing diagnostic test data from primary studies. Primary studies usually only provide binary test data, for which Moses et al. have developed a method to estimate Summary Receiver Operating Characteristic Curves, thereby taking account of possible test threshold differences between studies. Several methods are also available for analysing multicategory and continuous test data. The usefulness of applying these methods is constrained by publication bias and the generally poor quality of primary studies of diagnostic test accuracy. Meta-analysts need to highlight important defects in quality and how they affect summary estimates to ensure that better primary studies are available for meta-analysis in the future.

Bias↗
PubMed1995

PEAPS-Q: a questionnaire to measure the psychosocial effects of having an abnormal pap smear. Psychosocial Effects of Abnormal Pap Smears Questionnaire.

We have developed the Psychosocial Effects of Abnormal Pap Smears Questionnaire (PEAPS-Q) which measures distress experienced by women undergoing follow-up investigation after an abnormal Pap smear result. A thorough literature review and qualitative research resulted in the development of a questionnaire which was tested on 350 women attending a Family Planning New South Wales (FPNSW) clinic. This sample included women at different stages of management after detection of a cervical abnormality: 93 first colposcopy clients and 257 follow-up colposcopy clients. Factor analysis identified four dimensions of distress: experience of medical procedures, beliefs/feelings about cervical abnormality and changes in perception of oneself, worry about infectivity and effect on sexual relationships. Repeatability of the PEAPS-Q was indicated by intra-class correlations of 0.88 overall and at least 0.60 for each scale. Internal consistency was shown by Cronbach's alpha of 0.84 overall and at least 0.72 for each scale. Validity was demonstrated by the correlation of scale scores with the 12-item General Health Questionnaire (GHQ) score of 0.32 (95% CI 0.22-0.41). The PEAPS-Q is a valid, reliable and multidimensional instrument for quantifying distress experienced by women with abnormal Pap smears.

Adult↗
PubMed1995

The potential benefits and harms of screening for colorectal cancer.

Australian guidelines for colorectal cancer screening for average-risk populations vary from recommendations for annual screening by faecal occult blood testing for those over 40 years to recommendations that screening may be appropriate if requested by an informed patient aged 50 to 75 years. There are five large screening trials, of which three have published mortality data. A meta-analysis of the mortality data suggests a 19 per cent reduction in colorectal cancer mortality (95 per cent confidence intervals 0.68 to 0.96) with Hemoccult screening. Because of the width of the confidence interval, decisions about the magnitude of the effect of screening should await further trial results, which should be available in the next few years. In the interim, we should examine issues of harm and costs in Australia. For example, in the major trials, over 80 per cent of positive results have been falsely positive and have required invasive investigation. Estimates of the cost-effectiveness of screening for the Australian health system are not yet available and are essential. If the benefits of screening outweight the harms and costs, a successful screening program would require provision of screening infrastructure and appropriate information to target populations, quality control for screening tests and investigations, recall mechanisms to ensure appropriate follow-up of persons with positive results and the active participation of the Australian public and health practitioners.

Adult↗
PubMed1995

A prospective cohort study investigating psychosocial predictors of attendance at a mobile breast screening service.

This study aimed to examine whether knowledge, attitudes and concerns predicted attendance at the mobile Breast X-Ray Programme in Sydney. A cohort study design was used, whereby women were surveyed prior to the implementation of the program, and two years later records were checked to determine whether they had attended for screening. Telephone interviews were sought with randomly selected women aged 45 to 70 years living in the central Sydney area (the screening van's catchment area). A total of 285 women was surveyed (response rate: 50 per cent). Of these, 86 (30 per cent) subsequently attended at the mobile van and 199 did not. Attendance did not appear to be related to any of the following factors: knowledge; attitudes; prior experience; perceived susceptibility and morbid concern in relation to breast cancer; the amount of information about screening mammography to which a woman had been exposed. The results are interpreted in light of methodological considerations plus findings from our other research.

Aged↗
PubMed1994

n of 1 trials comparing a non-steroidal anti-inflammatory drug with paracetamol in osteoarthritis.

OBJECTIVE: To evaluate the efficacy of paracetamol and a non-steroidal anti-inflammatory drug for symptom relief in osteoarthritis. DESIGN: Double blind, randomised, controlled trials in individual patients (n of 1 trials). Three treatment cycles with two weeks' each of paracetamol (1 g twice daily) and diclofenac (50 mg twice daily) prepared in identical gelatin capsules. SETTING: General practices in metropolitan Sydney, Australia. SUBJECTS: 25 patients (median age 64 years) with pain of osteoarthritis (median duration of disease eight years) considered by their general practitioners to require regular treatment. 20 were already taking non-steroidal anti-inflammatory drugs. MAIN OUTCOME MEASURES: Diary of pain and stiffness, function, and side effects. RESULTS: 15 patients completed the study, five withdrew early but had made a therapeutic decision, and five dropped out very early. Results from 20 patients were analysed. Several patterns of response evolved. Eight of the 20 patients found no clear difference, symptoms being adequately controlled by paracetamol; five indicated a clear preference for the non-steroidal anti-inflammatory drug; two showed control of symptoms after their initial two weeks of the non-steroidal anti-inflammatory drug which continued throughout subsequent treatment changes; in five the non-steroidal anti-inflammatory drug may have been better but neither agent gave satisfactory control. After three months nine of the 20 patients had adequate symptom control with paracetamol alone. CONCLUSIONS: Of 1 studies--that is, randomised trials in individual patients--are clinically useful in deciding treatment in heterogeneous conditions which require long term symptomatic relief. In osteoarthritis many patients currently receiving or being considered for non-steroidal anti-inflammatory drugs may achieve adequate control with paracetamol.

Acetaminophen↗
PubMed1994

Efficient study designs to assess the accuracy of screening tests.

Evaluating a screening test often requires estimation of test sensitivity and specificity with appropriately narrow confidence intervals and at least cost. If the major cost is the reference ("gold") standard, savings arise from reducing the large number of test negatives that are verified by the reference standard. On the basis of the formulae of Begg and Greenes (Biometrics 1983;39:207-15), the authors determine the optimal sampling strategy for test positives and test negatives to minimize the total sample size that needs to be verified for a given confidence interval width for sensitivity. Unless sensitivity is very high, verifying more test positives and fewer test negatives than would occur with equal sampling fractions is appropriate. For example, if the sensitivity is 0.7 and the specificity is 0.99, the optimal sampling strategy is for 6.2% of those verified to be test positives, compared with 1.7% in the case of equal sampling fractions. At a disease prevalence of 0.01, the 3.3-fold increase in test positives results in a saving of about 15% in the test negatives and 11% in the total verified sample size. Overall, savings are about 50% for a sensitivity of 0.3, but are negligible when sensitivity is greater than 0.8. Optimal sampling strategies for sensitivity do not materially alter confidence intervals for specificity. Figures are presented from which readers can easily obtain the optimal sampling strategy given an estimate of specificity, approximated by the proportion of screenees who are test negative, and the range of likely sensitivity.

Algorithms↗
PubMed1994

Guidelines for meta-analyses evaluating diagnostic tests.

OBJECTIVES: To introduce guidelines for the conduct, reporting, and critical appraisal of meta-analyses evaluating diagnostic tests and to apply these guidelines to recently published meta-analyses of diagnostic tests. DATA SOURCES: Based on current concepts of how to assess diagnostic tests and conduct meta-analyses. They are applied to all meta-analyses evaluating diagnostic tests published in English-language journals from January 1990 through December 1991, identified through MEDLINE searching and by experts in the field. STUDY SELECTION: Meta-analyses were included if at least two of three independent readers regarded their main purpose as the evaluation of diagnostic tests against a concurrent reference standard. DATA EXTRACTION: By three independent readers on the extent to which meta-analyses fulfilled each guideline, with consensus defined as agreement by at least two readers. DATA SYNTHESIS: The guidelines are concerned with determining the objective of the meta-analysis, identifying the relevant literature and extracting the data, estimating diagnostic accuracy, and identifying the extent to which variability is explained by study design characteristics and characteristics of the patients and diagnostic test. In general, the guidelines were only partially fulfilled. CONCLUSION: Meta-analysis is potentially important in the assessment of diagnostic tests. Those reading meta-analyses evaluating diagnostic tests should critically appraise them; those doing meta-analyses should apply recently developed methods. The conduct and reporting of primary studies on which meta-analyses are based require improvement.

Bias↗
PubMed1994

The psychosocial impact of implementing a mammography screening campaign in an Australian community.

We examined the psychosocial impact of implementing a generalised campaign to promote mammography screening in an Australian inner city community. Prior to the campaign, telephone interviews were conducted with 628 randomly selected women aged 45-70, 285 in central Sydney (where the screening programme operated) and 343 from the rest of Sydney. A second cross-sectional survey was conducted two years after the campaign commenced. The campaign achieved an estimated 21% attendance rate in an eligible population of 43,000 women over a period of 22 months. Overall the campaign reached a large section of the eligible community, with 70% of women being aware of the van's existence. In addition, the proportion of women who reported being exposed to 'a moderate amount' or 'quite a lot' of information about screening increased by almost 20%. However, two thirds of women still reported being exposed to 'only a little' or no information at all. Attendance was achieved largely in the absence of improvements in knowledge and attitudes. Where change did happen, it occurred in the community overall, rather than being confined to the campaign's target area. Changes were most likely due to general electronic and print media messages, which were largely positive in their tone of reporting on screening. The campaign in one area of central Sydney, Drummoyne, which was much more intense, was successful in encouraging greater awareness of the van and mammography screening, plus greater attendance than in the rest of central Sydney, but had no impact on knowledge or attitudes. There was no demonstrable impact on psychological morbidity.

Adult↗
PubMed1994

Work-site cholesterol screening and dietary intervention: the Staff Healthy Heart Project. Steering Committee.

OBJECTIVES: The Staff Healthy Heart Project was established to run a work-site cholesterol screening project and a randomized controlled trial of dietary interventions. METHODS: Screening was offered to all staff at six Australian hospitals. Participants with blood cholesterol of 5.2 mmol/L (200 mg/dL) or above were randomly allocated to receive screening only (control group), a self-help package, or a nutrition course. Participants were seen 3 and 6 months after intervention to measure blood cholesterol and dietary changes. RESULTS: Eighty percent of available staff (n = 2638) were screened. Of those eligible, 67% (n = 683) entered the trial. Follow-up measures of blood cholesterol and dietary intake were obtained for 63% and 38% of trial participants, respectively. A reduction in reported dietary fat was found for all groups, but there were no significant differences between groups. Reported dietary fiber rose by 0.6 g/MJ/day for those in the nutrition course. There were no changes in total blood or high-density lipoprotein cholesterol. CONCLUSIONS: Cholesterol reduction was not demonstrated, but this result is difficult to interpret given the poor ongoing participation rates. Strategies to improve ongoing participation in work-site projects are needed to achieve adequate assessment of dietary interventions used in cholesterol screening.

Adolescent↗
PubMed1994

Environmental factors in childhood IDDM. A population-based, case-control study.

OBJECTIVE: To identify environmental factors involved in the etiology of insulin-dependent diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS: An estimated 90% of all incident cases of IDDM in patients 0-14 years of age in New South Wales, Australia, were ascertained over 18 months. For each IDDM patient, two age- and sex-matched control subjects were randomly selected from the population. Past environmental exposures were determined with a questionnaire completed by the parents. Response rates were 92% for the IDDM patients (217 of 235) and 55% for the control subjects (258 of 470). The relative risk associated with each exposure was estimated with the odds ratio (OR) adjusted for confounding factors using multiple logistic regression. RESULTS: The introduction of cow's milk-based infant formula into the diet before 3 months of age was associated with an increased risk (OR 1.52, 95% confidence interval [CI] 1.04-2.24). Exclusive breast-feeding for > or = 3 months was associated with a protective effect (OR 0.66, 95% CI 0.45-0.97). High dietary intake of cow's milk protein in the 12 months before the onset of diabetic symptoms was also associated with an increased risk (OR 1.84, 95% CI 1.12-3.00). A recent infection (during the 3 months before onset of diabetic symptoms) was more common in the patients than the control subjects (OR 2.92, 95% CI 1.96-4.35), as was day care attendance before the age of 3 (OR 1.73, 95% CI 1.00-3.00). When two age-groups, defined by the median age at onset of diabetes, were compared, the associations with early infant-feeding were stronger among the younger group (< 9.2 years), and associations with recent diet and recent infection were stronger among the older group (> or = 9.2 years). CONCLUSIONS: These results indicate an increased risk of IDDM associated with early dietary exposure to cow's milk-containing formula, short duration of exclusive breast-feeding, high intake of cow's milk protein in the recent diet, recent infection, and early attendance at day care.

Adolescent↗