Bias in meta-analysis detected by a simple, graphical test. Graphical test is itself biased.
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Meta-Analysis as Topic↗
Biomedical subjects
P Macaskill
Publications and source records attributed to P Macaskill.
Methods of the NSW Schools Fitness and Physical Activity Survey, 1997.
Physical fitness, participation in physical activity, fundamental motor skills and body composition are important contributors to the health and the development of a healthy lifestyle among children and youth. The New South Wales Schools Fitness and Physical Activity Survey, 1997, was conducted to fill some of the gaps in our knowledge of these aspects of the lives of young people in New South Wales. The survey was conducted in February and March, 1997 and collected data on a randomly-selected sample of students (n = 5518) in Years 2, 4, 6, 8 and 10. Measures were taken on body composition (height and weight, waist and hip girths, skinfolds), health-related fitness (aerobic capacity, muscular strength, muscular endurance, flexibility), fundamental motor skills (run, vertical jump, catch, overhand throw, forehand strike and kick), self-reported physical activity, time spent in sedentary recreation, and physical education (PE) classes. The methods are described to assist in the development of surveys of other populations and to provoke debate relevant to the development and dissemination of standard approaches to monitoring the fitness, physical activity habits and body composition of Australian children and youth. Finally, we offer comments on some of the strengths and limitations of the methods employed.
Anthropometry↗
Health risk and behaviour of out-of-school 16-year-olds in New South Wales.
This study describes the health risks and health behaviour of a sample of 283 out-of-school 16-year-olds in New South Wales. We sampled study participants through the Commonwealth Employment Service offices in 1994 using a multistage sampling procedure. Of those surveyed, 129 responded to a letter inviting them to participate and 154 were recruited opportunistically. This paper describes the study methods and results for self-reported binge drinking, weekly use of tobacco and marijuana, sexual abuse, physical abuse, drink-driving, violence, and use of health services, by sex and method of recruitment. High rates of substance use were observed. Reported substance use in the out-of-school group was consistently higher than for 16-year-olds in school, except for binge drinking for girls recruited by letter. Of the out-of-school group, 34 per cent reported weekly use of tobacco, marijuana and also binge drinking. Boys were more likely to report drink-driving than girls (28 per cent and 13 per cent respectively). Having been in trouble with police ranged from 32 per cent for girls recruited by letter to 75 per cent for boys recruited opportunistically. A high proportion of girls reported sexual abuse (34 per cent of the 'letter' group and 41 per cent of the 'opportunistic' group). Overall, 87 per cent of respondents had used health services in the previous year. The results indicate that this is a disadvantaged group of young people who are an important target for health service provision and interventions.
Adolescent↗
Multiple sclerosis in Australia: socioeconomic factors.
The data from an epidemiological study on multiple sclerosis in Australia have been analysed to determine the relation between the prevalence of the disease and educational level, and the association between level of disability and employment status. There was a significantly higher frequency of multiple sclerosis in those who left school at an older age and achieved a higher educational level. The explanation of this finding remains speculative and may be related to genetic or environmental factors. The study confirmed the recognised association between moderate-severe disability and divorce-separation and lower rates of employment.
Adolescent↗
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↗
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↗
The inter-relationship of premenstrual symptoms.
The prospective symptom reports of women seeking treatment for premenstrual symptoms and control subjects was investigated. In order to compare symptom reports from premenstrual symptom sufferers and control subjects a method of combining and analysing prospectively collected menstrual cycle symptom data is required. A technique that uses the time of onset of menses and the time of ovulation (as measured by urinary luteinizing hormone excretion) to standardize each cycle into 14 time points was developed. Summary factors were then empirically derived from data collected prospectively from 30 premenstrual symptom sufferers and 19 control subjects. Twenty-two mood symptoms were summarized into a single factor and the 29 most frequently occurring physical symptoms were summarized into two factors. Factor scores were calculated on the basis of these factors and the effect of time during the menstrual cycle on these scores examined. Both physical symptom factor scores increased significantly in the luteal phase for both the premenstrual symptom sufferer group and the control group. The single mood factor score increased significantly in the luteal phase for the premenstrual sufferer group but not for the control group, suggesting that the only qualitative difference between the groups was the presence of cyclic mood symptoms in the premenstrual symptom sufferer group. The premenstrual symptom sufferer group recorded significantly higher scores on each of the three factors than the control group. The correlation between the scores on each of the factors over three cycles was high both in the follicular and luteal phase suggesting that these factor scores provide a reproducible measure of menstrual cycle symptomatology.
Adult↗
Who has Pap smears in New South Wales? Patterns of screening across sociodemographic groups.
The aim of this study was to determine whether Pap smear screening at adequate intervals is associated with area of residence, frequency of consultations with a general practitioner, socioeconomic status and non-English-speaking background. A representative 10 per cent sample of women from New South Wales and the Australian Capital Territory, aged 25 to 69 years and registered with the Health Insurance Commission (Medicare) (N = 155,281) was used to obtain age, postcode, frequency of Pap smears and frequency of consultations with general practitioners in the three-year period from February 1985 to January 1988. Census data for each postcode area were used as an indicator of other socio-demographic characteristics. Age-specific screening rates did not vary between Sydney, Newcastle/Wollongong, Canberra, and nonmetropolitan areas. In all age groups, having had a smear was most strongly associated with the frequency with which a woman consulted a general practitioner. Women who visited a general practitioner at least four times a year on average were about twice as likely to have had a recent Pap smear as those who averaged less than one visit per year. Screening rates were lowest among women living in areas with the most non-English-speakers and the lowest socio-economic status. Sociodemographic factors and health service usage patterns influence the proportion of women who are currently being screened. Evaluation of interventions to improve Pap smear screening rates should consider whether the percentage of women screened increases overall, and also whether the imbalances in screening rates between different groups are diminishing.
Adult↗
Evaluation of two school smoking education programmes under normal classroom conditions.
OBJECTIVES: To assess the effectiveness of two school based smoking education projects in delaying onset of smoking behaviour and in improving health knowledge, beliefs, and values. DESIGN: Cluster randomised controlled trial of two projects taught under normal classroom conditions. Schools were allocated to one of four groups to receive the family smoking education project (FSE); the smoking and me project (SAM); both projects in sequence (FSE/SAM); or no intervention at all. SETTING: 39 schools in Wales and England matched for size and catchment profile. SUBJECTS: All first year pupils in the schools were included and were assessed on three occasions (4538 before teaching (1988), 3930 immediately after teaching (1989), 3786 at one year follow up (1990)). MAIN OUTCOME MEASURES: Self reported smoking behaviour (backed by saliva sample) and change in relevant health knowledge, beliefs, and values. RESULTS: No consistent significant differences in smoking behaviour, health knowledge, beliefs, or values were found between the four groups. For never smokers at baseline the rate of remaining never smokers in 1990 was 74% (594/804) in the control group, 65% (455/704) in the FSE group, 70% (440/625) in the SAM group, and 69% (549/791) in the FSE/SAM group (chi 2adj = 6.1, df = 3, p = 0.1). Knowledge about effects of smoking rose in all groups from a mean score of 5.4 in 1988 to 6.4 in 1989 and 6.5 in 1990. CONCLUSIONS: More comprehensive interventions than school health education alone will be needed to reduce teenage smoking. Other measures including further restrictions on access to cigarettes and on the promotion of tobacco products need to be considered. Further research will be needed to develop effective school based health education projects, which should be formally field tested under normal conditions before widespread dissemination.
Child↗
Population prevalence and correlates of stages of change in physical activity.
Stages of change for exercise, sociodemographic variables, and beliefs about the health benefits of exercise were obtained for a representative sample of Australian adults (N = 4404). Logistic regression analysis was used to examine the relationship between exercise stage of change and sociodemographic variables and beliefs about the benefits of exercise. Thirteen percent of respondents stated that they did not exercise and did not intend to start; 10% stated that they did not exercise but were thinking of starting; 16% stated that they exercise occasionally and were not thinking of doing more; 23% stated that they exercised occasionally and were thinking of doing more; and 38% stated that they exercised regularly and intended to continue. Intention to do more exercise generally decreased with increasing age, but increased with level of education. An increased frequency of exercise and an intention to do more exercise was associated with the belief that exercise would help to prevent heart disease and with a higher level of education. The results provide a useful profile of the exercise habits (and intention to change those habits) of population subgroups. Public communication campaigns on the benefits of physical activity should focus particularly on those who do not intend to exercise, older adults, and the less well educated.
Adolescent↗
Prevalences and perceptions of licit and illicit drugs among New South Wales secondary school students, 1989.
This paper presents findings on drug prevalences for licit and illicit drugs among New South Wales secondary school students (n = 3753) in late 1989. It also considers the accuracy of students' perceptions of the drug causing the most and fewest drug-related deaths. Data were analysed by age and gender, using logistic regression for the prevalence data. Findings indicate that licit drugs (tobacco, alcohol and analgesics) were the most frequently and widely used. Rates for illicit drugs were low, although there was some degree of experimental use of cannabis which increased amongst older males. Perceptions were found to be inaccurate in emphasising the dangers of the illicit drug heroin over those of the licit drugs tobacco and alcohol. Reasons for these findings are discussed, and more in-depth research recommended into the relationship between drug prevalences and perceptions for different age groups, and its relevance for planning drug prevention initiatives.
Adolescent↗
Changes in reported drug prevalence among New South Wales secondary school students, 1983 to 1989.
Three drug use surveys employing a standardised questionnaire format and sampling procedure were conducted on samples of New South Wales school students in 1983, 1986 and 1989. Alcohol and tobacco were the most frequently used substances across the surveys, with rates of use of illicit substances being considerably lower. Declines in the prevalence of alcohol, tobacco and stimulant use were found between 1983 and 1986 and between 1986 and 1989 for both males and females. Rates of use of inhalants, sedatives, hallucinogens and narcotics declined between 1983 and 1986, but remained unchanged between the 1986 and 1989 samples. Cannabis use declined significantly among females between 1983 and 1989, but not among males. Possible reasons for the general decline in drug use over the six-year period are discussed.
Adolescent↗
Mass media-led antismoking campaign can remove the education gap in quitting behavior.
This study investigated whether the effective mass media-led antismoking campaigns in Australia had the traditional differential effect across educational levels. Our population surveys included random samples of 12,851 people before the campaign and 11,609 several years after the campaign had started. No statistically significant differences were found in quitting across education levels in three of the four subgroups. Mass media-led antismoking campaigns may play an important role in getting the antismoking message to the less educated.
Adult↗
Estimating an individual's true cholesterol level and response to intervention.
An individual's blood cholesterol measurement may differ from the true level because of short-term biological and technical measurement variability. Using data on the within-individual and population variance of serum cholesterol, we addressed the following clinical concerns: Given a cholesterol measurement, what is the individual's likely true level? The confidence interval for the true level is wide and asymmetrical around extreme measurements because of regression to the mean. Of particular concern is the misclassification of people with a screening measurement below 5.2 mmol/L who may be advised that their cholesterol level is "desirable" when their true level warrants further action To what extent does blood cholesterol change in response to an intervention? In general, confidence intervals are too wide to allow decision making and patient feedback about an individual's cholesterol response to a dietary intervention, even with multiple measurements. If no change is observed in an individual's cholesterol value based on three measurements before and three after dietary intervention, the 80% confidence interval ranges from a true increase of 4% to a true decrease of 9%.
Adult↗
A seroepidemiological study of hepatitis B amongst Fiji health care workers.
Hepatitis B immunization for health care workers is common policy in many countries where they constitute a particular at risk group. A seroepidemiological study of hepatitis B virus (HBV) in Fiji health care workers was conducted to determine whether this occupational group (or subgroups thereof) were at higher risk of infection than the general Fiji population. The purpose of this study was to ascertain whether health staff should be immunized, or whether it would be more productive to focus resources on neonatal immunization. Blood samples were obtained from 2,639 health workers and the sera analysed by radio-immunoassay for hepatitis B surface antigen (HBsAg), and hepatitis B surface antibody (anti-HBs). Prevalence rates of HBV markers of infection were compared with those observed in the general population, from a previous population-based cluster sample survey. Approximately 70% of the health care staff participated in the study. Prevalence of total HBV markers was 24%. The rate of HBsAg was 5%. Sex and ethnic group specific prevalence rates varied. Male subjects, Fijians and "other" Pacific Islanders all experienced higher rates of infection. Rural/urban and age related trends were also observed. Rates of infection in health staff were lower than those reported in the general population. Previous studies have indicated that most of the transmission of hepatitis B in hyperemdemic Pacific populations occurs at birth or within the next few years. There was no consistent pattern of hepatitis B infection in different occupational groups of health care workers. Certain relatively socially homogeneous subgroups of health workers were analysed separately, and among these health workers there was evidence for increased risk of infection due to exposure to blood or used hypodermic syringes, but not due to patient contact. Until health staff assume a higher risk of infection than the general Fijian population, efforts directed at community-wide control of hepatitis B continue to be the most appropriate use of resources.
Adolescent↗
Pap smear rates in New South Wales--1984 to 1988.
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Adult↗
The effect of a needle and syringe exchange on a methadone maintenance unit.
In November 1986, a pilot needle and syringe exchange was established in Sydney adjacent to a methadone maintenance unit. A retrospective study was carried out to determine the effect of increasing the availability of sterile needles and syringes on the treatment outcome of the methadone maintenance unit. In this study, an increase in availability of sterile needles and syringes was not found to be associated with an increase in the presence of illicit injectable drugs in the urine specimens of clients of the methadone programme compared to a control methadone unit where there was no known change in needle and syringe availability. This study suggests that an increase in the availability of sterile needles and syringes does not appear to lead to an increase in the frequency of intravenous drug use. The possibility of drug and alcohol treatment centres acting as needle and syringe exchange or distribution outlets therefore requires consideration.
Australia↗
Long-term effectiveness of mass media led antismoking campaigns in Australia.
A community antismoking campaign began in Sydney, Australia in 1983, and in Melbourne in 1984. These campaigns purchased prime-time television advertising spots to set the community agenda. An intense effort was made to ensure that antismoking activities were maximized at the school, organizational, and community level. Smoking prevalences in both cities from 1981 were fitted with a statistical model to identify any underlying trend, to assess any immediate impact, and to assess the longer term effect of continuing to conduct such campaigns, i.e. to identify any change in the underlying trend. During the years before the antismoking campaigns, there was no observable trend in smoking prevalence in either city. At the beginning of the campaigns, there was an immediate drop of more than two percentage points in male and female smoking prevalence in both cities. Thereafter, a decline of about 1.5 percentage points per year was observed among males. No post campaign trend was observed in smoking prevalence for women in either city. These data support conducting coordinated community campaigns to reduce current smoking prevalence.
Adolescent↗