The natural history of bone marrow lesions in community-based adults with no clinical knee osteoarthritis

OBJECTIVE

Although bone marrow lesions (BML) have been implicated in the pathogenesis of osteoarthritis, their natural history in a healthy population is unknown. This study in a healthy, pain-free population aimed to examine the natural history of BML; factors associated with incidence and progression of BML over 2 years and whether incident BML are associated with the development of pain.

METHODS

271 subjects with no clinical knee osteoarthritis, being pain free at baseline, underwent magnetic resonance imaging of their dominant knee at baseline and 2 years later. The presence of BML was assessed.

RESULTS

In knees initially free of BML, incident BML developed in 14% of people over the study period. Increased body mass index (BMI; odds ratio (OR) 1.15, 95% CI 1.06 to 1.2, p = 0.001) was associated with incident BML. Those who developed a BML were more likely to develop knee pain compared with those in whom no BML developed (OR 4.2, 95% CI 1.2 to 15.1, p = 0.03). Among those in whom BML were present at baseline, 46% completely resolved. There was no association between age, gender and BMI and persistence of BML over 2 years.

CONCLUSION

In this healthy population, the rate of incident BML is lower than previously described in a population with osteoarthritis. Incident BML are associated with increased BMI and the development of pain. Approximately half the BML present at baseline resolved. These data suggest that in pain-free people with no clinical knee osteoarthritis, BML are reversible and may provide a target for interventions aimed at the prevention of knee osteoarthritis.

Effect of fatty acids on bone marrow lesions and knee cartilage in healthy, middle-aged subjects without clinical knee osteoarthritis

OBJECTIVE

There is evidence that omega-3 polyunsaturated fatty acids alleviate the progression of osteoarthritis (OA). However, little work has been done to investigate the effect of fatty acids on bone marrow lesions and knee cartilage in healthy subjects. We examined this in a cohort of healthy middle-aged subjects without clinical knee OA.

METHODS

Two hundred and ninety-three healthy adults without knee pain or injury were recruited from an existing community-based cohort. Intakes of fatty acids and food sources of these were estimated from a food frequency questionnaire at baseline. Tibial cartilage volume, tibial plateau bone area, tibiofemoral cartilage defects and bone marrow lesions were assessed approximately 10 years later using magnetic resonance imaging.

RESULTS

In multivariate analyses, higher intakes of monounsaturated fatty acids (OR=2.14, 95% CI 1.04-4.39, P=0.04), total (OR=1.77, 95% CI 1.13-2.77, P=0.01) and n-6 polyunsaturated fatty acids (OR=1.69, 95% CI 1.10-2.61, P=0.02) were associated with an increased risk of bone marrow lesions. Intake of fatty acids was not significantly associated with cartilage volume or cartilage defects.

CONCLUSION

These findings support the dietary recommendation towards a shift to foods rich in n-3 polyunsaturated fatty acids in order to maintain an optimal balance between dietary n-3 and n-6 polyunsaturated fatty acids, which is also important in the prevention of atherosclerosis. Although our findings will need to be confirmed in longitudinal studies, they suggest the potential of fatty acids to adversely effect the knee joint.

The relationship between the angle of the trochlear groove and patella cartilage and bone morphology--a cross-sectional study of healthy adults

OBJECTIVES

Although the geometry of the trochlear groove is considered important in the pathogenesis of patellofemoral joint pathology it is unclear how the shape of the trochlear groove relates to patella morphology. This cross-sectional study investigated the relationship between the shape of the trochlear groove and patella cartilage and bone morphology in healthy adults.

METHODS

Two hundred and ninety-seven healthy adults aged between 50 and 79 years with no clinical history of knee pain or pathology were examined using magnetic resonance imaging (MRI). From the magnetic resonance (MR) images, the bony angles formed at the distal and proximal trochlear groove were measured, together with patella cartilage and bone volumes and patella cartilage defects.

RESULTS

After adjustment for potential confounders, there was an 8.70mm(3) (95% confidence interval (CI) 2.15, 15.26) increase in patella cartilage volume (P=0.009), with no increased prevalence of cartilage defects (odds ratio=0.99 (95% CI 0.96, 1.02), P=0.35), for every 1 degrees increase (i.e., as the angle became more flatter) at the distal trochlear groove. Moreover, there was a 53.86mm(3) (95% CI -90.26, -17.46) reduction in patella bone volume for every 1 degrees that the angle at the distal trochlear groove became more flattened (P=0.004). No significant association between the proximal trochlear groove angle and the patella cartilage or bone properties was observed.

CONCLUSION

A more flattened bony angle at the distal trochlear groove was associated with increased patella cartilage volume and reduced patella bone volume, but no increased prevalence of patella cartilage defects in adults with no history of knee pain or clinical disease. These cross-sectional findings suggest that a flattened distal trochlear groove may protect against degenerative patellofemoral conditions, such as osteoarthritis, but this will need to be confirmed in a longitudinal study.

A positive association of smoking and articular knee joint cartilage in healthy people

OBJECTIVE

To determine whether smoking affects knee cartilage in healthy adults by examining the association of tobacco use with tibial cartilage volume and tibiofemoral cartilage defects.

METHODS

Two hundred and ninety-seven healthy adult subjects were recruited from an existing cohort examining healthy aging, the Melbourne Collaborative Cohort Study (MCCS). Questionnaire data were obtained at recruitment to the MCCS in 1990-1994 and at magnetic resonance imaging to determine cartilage outcomes in 2003.

RESULTS

Tibial cartilage volume was positively associated with subjects who ever smoked as well as pack-years smoked, suggesting a dose-response. There was no association between smoking and presence of tibiofemoral cartilage defects.

CONCLUSION

Our findings demonstrate that smoking is associated with increased tibial cartilage volume but not presence of tibiofemoral cartilage defects, providing further support for a beneficial effect on articular knee cartilage.

Alcohol intake, consumption pattern and beverage type, and the risk of Type 2 diabetes

AIMS

To examine associations between amount and frequency of alcohol consumption, and Type 2 diabetes.

METHODS

A prospective study of 36 527 adults aged 40-69 at baseline. Incident cases of Type 2 diabetes were identified by questionnaire 4 years later. Sex-specific logistic regression models, adjusting for country of birth, dietary glycaemic index, energy intake and age, and in a second model body mass index (BMI) and waist-hip ratio (WHR), were used.

RESULTS

Diabetes status was ascertained for 31 422 (86%) participants, and 362 cases identified. Former drinkers had higher risks than lifetime abstainers. Female drinkers had lower risk than lifetime abstainers (ORs < 10 g/day 0.54, 95% CI 0.36-0.82; 10-19.9 g/day 0.57, 0.34-0.94; > or = 20 g/day 0.46, 0.24-0.88, P trend = 0.005). There was no relationship after adjustment for body size. For men, a weak inverse association was observed after adjustment for body size (ORs relative to lifetime abstainers: < 10 g/day 1.56, 0.95-2.55; 10-19.9 g/day 1.21, 0.69-2.10; 20-29.9 g/day 0.80, 0.40-1.60; = 30 g/day 0.86, 0.50-1.58, P trend = 0.036). Wine was the only beverage for which an inverse association was observed. Compared with men who did not drink in the week before baseline, men who drank > or = 210 g over 1-3 days had an increased risk of diabetes (OR 5.21, 1.79-15.19), while the same amount over more days did not increase risk.

CONCLUSIONS

Total alcohol intake was associated with reduced risk only in women. Alcohol from wine was associated with reduced risk of Type 2 diabetes. A high daily intake of alcohol, even on only 1-3 days a week, may increase the risk of diabetes in men.

Physical activity, insulin-like growth factor 1, insulin-like growth factor binding protein 3, and survival from colorectal cancer

BACKGROUND

Recent reports have shown that physical activity improves the outcome of patients with colorectal cancer as well as breast and prostate cancer. However, the mechanisms whereby physical activity reduces cancer mortality are not well established.

METHODS

Incident cases of colorectal cancer were identified among participants of the Melbourne Collaborative Cohort Study, a prospective cohort study of 41,528 Australians recruited from 1990 to 1994. Information on tumour site and stage, treatments given, recurrences, and deaths were obtained from systematic review of the medical records. Baseline assessments of physical activity and body size were made, and cases with available plasma had pre-diagnosis insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) levels measured. We assessed associations between these hormones and colorectal cancer specific deaths with respect to physical activity.

RESULTS

A total of 526 cases of colorectal cancer were identified, of which 443 had IGF-1/IGFBP-3 levels measured. Median follow up among survivors was 5.6 years. For the physically active, increasing IGFBP-3 by 26.2 nmol/l was associated with a 48% reduction in colorectal cancer specific deaths (adjusted hazard ratio (HR) 0.52 (0.33-0.83); p = 0.006). No association was seen for IGF-1 (adjusted HR 0.90 (0.55-1.45); p = 0.65). For the physically inactive, neither IGF-1 nor IGFBP-3 was associated with disease specific survival.

CONCLUSIONS

This study supports the hypothesis that the beneficial effects of physical activity in reducing colorectal cancer mortality may occur through interactions with the insulin-like growth factor axis and in particular IGFBP-3.

A comparison of estradiol levels between women with a hysterectomy and ovarian conservation and women with an intact uterus

OBJECTIVES

To compare the distribution of estradiol levels between women with a hysterectomy and ovarian conservation and women with an intact uterus.

METHODS

A large cross-sectional study of women aged between 40 and 69 years, residing in Melbourne, Australia. Estradiol levels were available for 152 women with a hysterectomy and ovarian conservation and 1423 women with an intact uterus. All of the women were 'never-users' of hormone replacement therapy.

RESULTS

For women under 55 years of age, we observed that those with a hysterectomy and ovarian conservation had slightly higher estradiol levels compared with those with an intact uterus after adjustment for age, body mass index, smoking status and alcohol intake (ratio of geometric means of estradiol levels = 1.24; 95% confidence interval = 1.00-1.53). For women who were 55 years or greater, the distribution of estradiol levels varied little by hysterectomy status.

CONCLUSIONS

Our data do not suggest that women with hysterectomy and ovarian conservation have markedly different estradiol levels compared to women with an intact uterus.

Effect of physical activity and body size on survival after diagnosis with colorectal cancer

BACKGROUND

Physical inactivity and obesity increase the risk of colorectal cancer but little is known about whether they influence prognosis after diagnosis.

METHODS

Incident cases of colorectal cancer were identified among participants of the Melbourne Collaborative Cohort Study, a prospective cohort study of 41 528 Australians recruited from 1990 to 1994. Participants diagnosed with their first colorectal cancer between recruitment and 1 August 2002 were eligible. At the time of study entry, body measurements were taken and participants were interviewed about their physical activity. Information on tumour site and stage, treatments given, recurrences, and deaths were obtained from systematic review of the medical records.

RESULTS

A total of 526 cases of colorectal cancer were identified. Median follow up among survivors was 5.5 years, and 208 deaths had occurred, including 181 from colorectal cancer. After adjusting for age, sex, and tumour stage, exercisers had an improved disease specific survival (hazard ratio 0.73 (95% confidence interval (CI) 0.54-1.00)). The benefit of exercise was largely confined to stage II-III tumours (hazard ratio 0.49 (95% CI 0.30-0.79)). Increasing per cent body fat resulted in an increase in disease specific deaths (hazard ratio 1.33 per 10 kg (95% CI 1.04-1.71)). Similarly, increasing waist circumference reduced disease specific survival (hazard ratio 1.20 per 10 cm (95% CI 1.05-1.37)).

CONCLUSIONS

Increased central adiposity and a lack of regular physical activity prior to the diagnosis of colorectal cancer is associated with poorer overall and disease specific survival.

Creating SunSmart schools

Kidskin was a sun-protection intervention study involving 1776 children attending 33 primary schools in Perth, Western Australia. There were three study groups: a control group, a moderate intervention group and a high intervention group. In addition to receiving a specially designed curricular intervention (1995-1998), the moderate and high intervention groups received an environmental intervention aimed at creating SunSmart schools (1996-1998). The environmental intervention focused on encouraging implementation of 'No hat, no play' policies and reducing sun exposure at lunchtime. In 1995 and 1998, observational methods were used to measure children's lunchtime sun exposure (i.e. polysulfone film badges) and hat wearing (i.e. video-taping of children). The proportion of children wearing broad-brimmed hats or legionnaire caps increased in seven of the eight high intervention schools between 1995 and 1998. In three schools, however, the impact was very positive with almost all children wearing these hats in 1998. There was no improvement in wearing these types of hats in either the moderate intervention group or the control group. In terms of sun exposure, there were only small non-significant differences among the three groups in terms of lunchtime sun exposure. The Kidskin program had a positive effect on hat wearing in the playground, but did not change children's use of shade at lunchtime. In this study, disseminating policy guidelines to schools using a mail-only strategy was ineffective, even when combined with an awards program. More information on 'champions' who bring about change in schools is required.

Androgenetic alopecia in men aged 40-69 years: prevalence and risk factors

BACKGROUND

The epidemiology of androgenetic alopecia (AGA) is not fully understood. Although a strong genetic basis has long been identified, little is known of its non-genetic causes.

OBJECTIVES

To estimate the prevalence of and to determine risk factors for AGA in men aged 40-69 years in Australia.

METHODS

Men (n = 1390) were recruited at random from the electoral rolls to serve as controls in a population-based case-control study of prostate cancer. All were interviewed in person and direct observations of AGA were made. Men were grouped into the following categories; no AGA, frontal AGA, vertex AGA and full AGA (frontal and vertex AGA). Epidemiological data collected from these men were used for an analysis of risk factors for each AGA category using unconditional logistic regression with AGA category as the response variable adjusting for age, education and country of birth.

RESULTS

The prevalence of vertex and full AGA increased with age from 31% (age 40-55 years) to 53% (age 65-69 years). Conversely, the proportion of men with only frontal AGA was very similar across all age groups (31-33%). No associations were found between pubertal growth spurt or acne, reports of adult body size at time of interview, urinary symptom score, marital status, or current smoking status or duration of smoking and the risk of any form of AGA. The consumption of alcohol was associated with a significant increase in risk of frontal and vertex AGA but not full AGA. Men with vertex AGA had fewer female sexual partners but average ejaculatory frequency did not differ between men in different AGA categories. Reported weight and lean body mass at reaching maturity at about 21 years of age were negatively associated with vertex balding (P for trend < 0.05) but not with frontal AGA or full AGA.

CONCLUSIONS

Evidence for environmental influences on AGA remains very slight. Our study failed to confirm previously reported or hypothesized associations with smoking and benign prostatic hypertrophy. The associations that we found with alcohol consumption and with lean body mass at age 21 years would be worthy of further research if they were able to be replicated in other studies.

Sexual factors and prostate cancer

OBJECTIVE

To assess whether prostate cancer might be related to hormone levels and, by inference, to differences in sexual activity.

PATIENTS, SUBJECTS AND METHODS

In a case-control study of men with prostate cancer aged < 70 years at diagnosis and age-matched control subjects, information was collected on two aspects of sexual activity; the number of sexual partners and the frequency of total ejaculations during the third to fifth decades of life.

RESULTS

There was no association of prostate cancer with the number of sexual partners or with the maximum number of ejaculations in 24 h. There was a negative trend (P < 0.01) for the association between risk and number of ejaculations in the third decade, independent of those in the fourth or fifth. Men who averaged five or more ejaculations weekly in their 20s had an odds ratio (95% confidence interval) of 0.66 (0.49-0.87) compared with those who ejaculated less often.

CONCLUSIONS

The null association with the number of sexual partners argues against infection as a cause of prostate cancer in this population. Ejaculatory frequency, especially in early adult life, is negatively associated with the risk of prostate cancer, and thus the molecular biological consequences of suppressed or diminished ejaculation are worthy of further research.

Risk of prostate cancer associated with a family history in an era of rapid increase in prostate cancer diagnosis (Australia)

OBJECTIVE

We conducted a case-control study of prostate cancer and familial risk of the disease in Australia between 1994 and 1998, a period during which the incidence of prostate cancer increased dramatically with widespread use of prostate-specific antigen (PSA) testing.

METHODS

1475 cases and 1405 controls were asked about prostate cancer in their first-degree relatives. Odds ratios (OR) were calculated using logistic regression.

RESULTS

Cases were more likely to report a family history of prostate cancer than controls (OR 3.0; 95% confidence interval (CI) 2.3-3.9) and cases reporting an affected relative were younger (58.8 versus 60.9 years, p < 0.0001). The OR for an affected first-degree relative increased with increasing number of affected relatives and decreased with increasing age of the case. The OR for more than one affected first-degree relative was 6.9 (95% CI 2.7-18). The OR for an affected brother was 3.9 (95% CI 2.5-6.1) and for an affected father was 2.9 (95% CI 2.1-3.9) but these were not significantly different (p = 0.2). When analyses were repeated including only diagnoses made in relatives prior to 1992, the risks were generally similar except that the OR for an affected brother decreased to 3.1 (95% CI 1.2-3.9). When only relatives' diagnoses made after 1991 were included results were again similar to those for all relatives, although the effect for brothers was greater and the attenuation with age at diagnosis dissipated.

CONCLUSIONS

The recent introduction of PSA testing that has resulted in a greater prevalence of apparent prostate cancer, does not appear to have substantially altered familial risks of disease, although effects associated with brothers may be inflated.

Prevalence of urinary symptoms in urban Australian men aged 40-69

BACKGROUND

This study was devised to determine the prevalence of urinary symptoms among men living in the Australian cities of Melbourne, Sydney or Perth, and to identify factors associated with the presence of moderate-to-severe urinary symptoms.

METHODS

The study comprised a population-based sample of 1,216 men, aged 40-69 years, whose names were obtained through electoral rolls and who participated as controls in a case-control study of risk factors for prostate cancer. As part of a structured face-to-face interview, the men completed the International Prostate Symptom Score (IPSS). Men with moderate (IPSS = 8-19) or severe (IPSS > or = 20) urinary symptoms were compared with those with mild or no symptoms (IPSS < 8) using unconditional logistic regression.

RESULTS

The age-specific prevalence of moderate-to-severe urinary symptoms (IPSS > or = 8) in men aged 40-49, 50-59, 60-69 years was 16%, 23% and 28%, respectively. Compared with men with no or mild urinary symptoms (IPSS < 8), men with moderate-to-severe symptoms were more likely to report not currently living as married [odds ratio (OR) = 1.5; 95% confidence interval (CI) 1.1-2.0] and being circumcised (OR = 1.5; 95% Cl 1.2-2.0). The increased likelihood associated with drinking an average of > 60 g day(-1) of alcohol in the 2 years before interview was of marginal statistical significance (OR = 1.6; 1.0-2.6). There were no significant differences between men with IPSS > or = 8 and those with IPSS < 8 with respect to body mass index, education level, having had a vasectomy, or cigarette smoking.

CONCLUSION

Among Australian men, being circumcised, or not currently living as married, were associated with increased prevalence of urinary symptoms.

Reduced sun exposure and tanning in children after 2 years of a school-based intervention (Australia)

OBJECTIVE

This paper presents the results of the evaluation of measured suntan and parent-reported sun exposure in participating children after 2 years of the Kidskin study, a 5-year school-based sun protection intervention undertaken in Perth, Western Australia (1995-1999).

METHODS

The study involves three groups: a control, a "moderate", and a "high" intervention group. Participants were 5 or 6 years of age at the beginning of the study. Control schools received the standard Health Education curriculum, while intervention schools received a multicomponent intervention including a specially designed curriculum. Children in the high intervention group also received program materials over the summer vacation and were offered sun-protective swimwear at low cost. At the end of the second summer, suntan was measured and parents completed a questionnaire about their child's sun-related behavior.

RESULTS

Children in the intervention groups--especially the high group--were less tanned at the end of the summer; this effect was greater for the back than for the forearms. These children were also reported to have received less sun exposure and made greater use of sun protection measures.

CONCLUSION

Intensive school-based interventions can reduce tanning and reported sun exposure in children.

Smoking and prostate cancer: findings from an Australian case-control study

BACKGROUND

To examine the risk of smoking on histopathologically-confirmed moderate- and high-grade prostate cancer.

MATERIALS AND METHODS

A population-based case-control study was conducted in Melbourne, Sydney and Perth between 1994 and 1998 in men aged below 70 years. Cases were recruited from cancer registries and controls were selected from electoral registers. 1498 cases and 1434 controls were interviewed and a detailed smoking history obtained. Data were analyzed by unconditional logistic regression, adjusting for age, study center, year of recruitment, family history and country of birth.

RESULTS

The odds ratios (OR) were 1.02 (0.85-1.22) for former smoking and 0.82 (0.65-1.05) for current smoking. The respective ORs were 0.95 (0.78-1.15) and 0.76 (0.59-0.99) for moderate grade tumors, and 1.28 (0.96-1.70) and 1.00 (0.67-1.47) for high-grade tumors (P = 0.2 for test that ORs of the two grades were identical). There was no evidence of a dose-response effect for duration of smoking, amount smoked daily, pack-years of smoking and years since quitting and most ORs for these variables were close to unity.

CONCLUSIONS

Smoking was not associated with the incidence of prostate cancer. The widths and upper limits of the confidence intervals for the effects of current and former smoking were consistent with weak effects at most.

Segregation analyses of 1,476 population-based Australian families affected by prostate cancer

Segregation analyses aim to detect genetic factors that have a major effect on an individual's risk of disease and to describe them in terms of mode of inheritance, age-specific cumulative risk (penetrance), and allele frequency. We conducted single- and two-locus segregation analyses of data from 1,476 men with prostate cancer diagnosed at age <70 years and ascertained through population registries in Melbourne, Sydney, and Perth, Australia, and from their brothers, fathers, and both maternal and paternal lineal uncles. Estimation and model selection were based on asymptotic likelihood theory and were performed through use of the software MENDEL. All two-locus models gave better fits than did single-locus models, even if lineal uncles were excluded or if we censored data (age and disease status) for relatives at 1992, when prostate-specific-antigen testing started to have a major impact on the incidence of prostate cancer in Australia. Among the genetic models that we considered, the best-fitting ones included a dominantly inherited increased risk that was greater, in multiplicative terms, at younger ages, as well as a recessively inherited or X-linked increased risk that was greater, in multiplicative terms, at older ages. The recessive and X-linked effects were strongly confounded, and it was not possible to fit them together. Penetrance to age 80 years was approximately 70% (95% confidence interval [CI] 57%-85%) for the dominant effect and virtually 100% for the recessive and X-linked effects. Approximately 1/30 (95% CI 1/80-1/12) men would carry the dominant risk, and 1/140 (95% CI 1/220-1/90) would carry the recessive risk or 1/200 (95% CI 1/380-1/100) would carry the X-linked risk. Within discussed limitations, these analyses confirm the genetic heterogeneity, of prostate cancer susceptibility, that is becoming evident from linkage analyses, and they may aid future efforts in gene discovery.

A psychometric experiment in causal inference to estimate evidential weights used by epidemiologists

A psychometric experiment in causal inference was performed on 159 Australian and New Zealand epidemiologists. Subjects each decided whether to attribute causality to 12 summaries of evidence concerning a disease and a chemical exposure. The 1,748 unique summaries embodied predetermined distributions of 19 characteristics generated by computerized evidence simulation. Effects of characteristics of evidence on causal attribution were estimated from logistic regression, and interactions were identified from a regression tree analysis. Factors with the strongest influence on the odds of causal attribution were statistical significance (odds ratio = 4.5 if 0.001 < or = P < 0.05 and 7.2 if P < 0.001, vs P > or = 0.05); refutation of alternative explanations (odds ratio = 8.1 for no known confounder vs none adjusted); strength of association (odds ratio = 2.0 if 1.5 < relative risk < or = 2.0 and 3.6 if relative risk > 2.0, vs relative risk < or = 1.5); and adjunct information concerning biological, factual, and theoretical coherence. The refutation of confounding reduced the cutpoint in the regression tree for decision-making based on strength of association. The effect of the number of supportive studies reached saturation after it exceeded 12 studies. There was evidence of flawed logic in the responses concerning specificity of effects of exposure and a tendency to discount evidence if the P-value was a "near miss" (0.050 < P < 0.065). Evidential weights based on regression coefficients for causal criteria can be applied to actual scientific evidence.

Improved sun protection behaviour in children after two years of the Kidskin intervention

OBJECTIVE

To evaluate a school-based intervention in terms of reducing children's sun exposure and improving their use of sun protection measures.

METHODS

'Kidskin' is a five-year, school-based intervention study in Perth, Western Australia, of a cohort of children who were five or six years old in 1995. The study involves three groups: control, 'moderate' and 'high' intervention. Children in the control schools received the standard health curriculum; those in the intervention schools received a multicomponent intervention, including a specially designed curriculum. Children in the high intervention group also received program materials over the summer holidays and were offered sun-protective swimwear at a low cost. After two years, parents completed a questionnaire about their child's sun-related behavior.

RESULTS

Children in the intervention groups--especially the 'high' group--were reported to have had less sun exposure. This involved covering the back more often, spending more time in the shade when outdoors and wearing a style of swimsuit that covered the trunk. There was also evidence that children in the intervention groups spent less time outdoors in the middle of the day. There was little difference between groups in the wearing of hats or sunscreen.

CONCLUSIONS

Our school-based intervention improved children's sun protection, but had little effect on specific behaviours that have already been vigorously promoted.

IMPLICATIONS

School-based prevention campaigns would benefit from focusing on sun protection using clothing and shade, and reducing sun exposure in the middle of the day. There may be little potential to improve hat and sunscreen use.

The age-range of risk of developing multiple sclerosis: evidence from a migrant population in Australia

The prevalence of multiple sclerosis in the Australian-born population in five different regions of Australia has a strong correlation with latitude, the disease becoming increasingly prevalent with increasing south latitude. In this study, the prevalence in the migrant population from the UK and Ireland (UKI) in the different regions also showed a significant correlation with latitude, but this relationship was strongly influenced by the high prevalence in Hobart. Except for Hobart, the prevalence in migrants was considerably less than that in their countries of origin. The prevalence of multiple sclerosis among those migrating before the age of 15 years from the high-risk UKI to lower-risk Australia was not significantly different to that among those migrating at or after that age, and this finding was confirmed in a case-control study which demonstrated little association between age at migration and risk of developing multiple sclerosis. These findings suggest that the risk from environmental factors in multiple sclerosis may operate over a period of many years and not only in childhood and early adult life.

Multiple sclerosis in Australia: prognostic factors

In order to determine the influence of age of onset, sex, onset symptoms, clinical course and interval from onset to first relapse on the subsequent outcome of multiple sclerosis (MS), data from 2934 cases of MS documented in a large population based study undertaken in Australia have been analysed. Disability on prevalence day (30 June 1981) was defined on the Kurtzke disability scale as mild (DSS 0-3), moderate (DSS 4-6) and severe (DSS 7-9). Prognostic factors associated with mild vs moderate/severe, and moderate vs severe disability on prevalence day were identified by logistic regression analysis. A worse prognosis was significantly associated with older age of onset, progressive disease course, onset symptoms that were multiple, pyramidal or cerebellar, and a short interval between onset and first relapse.