Reliability of the Hammersmith functional motor scale for spinal muscular atrophy in a multicentric study.

The aim of this study was to validate the Hammersmith functional motor scale for children with spinal muscular atrophy in a large cohort of 90 non-ambulant children with spinal muscular atrophy type 2 or 3. All had a baseline assessment (T0) and were reassessed either at 3 months (T1) (n = 66) or at 6 months (T2) (n = 24). Inter-observer reliability, tested on 13 children among 3 examiners, was > 95%. Of the 66 children examined after 3 months 4 had adverse effects in between assessments and were excluded from the analysis. Forty-two (68%) of the remaining 62 reassessed had no variation in scores between T0 and T1 and 13 (21%) were within +/- 1 point. 9 (37.5%) of the 24 children reassessed after 6 months had no variation in scores between T0 and T2 and another 9 (37.5%) had variations within +/- 1 point. Our study confirms previous observations of the reliability of the scale and helps to establish a baseline for assessing changes of functional ability over 3 and 6 month intervals. This information can be valuable in view of therapeutic trials.

Corticosteroids for Guillain-Barré syndrome.

BACKGROUND: The cause of Guillain-Barré syndrome is inflammation of the peripheral nerves, which corticosteroids would be expected to benefit. OBJECTIVES: To examine the ability of corticosteroids to hasten recovery and reduce the long-term morbidity from Guillain-Barré syndrome. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Register (May 2005), MEDLINE (January 2000 to May 2005) and EMBASE (January 1980 to May 2005) and contacted trial authors and other experts. SELECTION CRITERIA: We included quasi-randomised or randomised controlled trials of people of all ages and all degrees of severity of Guillain-Barré syndrome who were treated with any form of corticosteroid or adrenocorticotrophic hormone. Our primary outcome measure was change in disability grade on a commonly used, validated seven-point scale at four weeks after randomisation. Secondary outcome measures were: time from randomisation until recovery of unaided walking, time from randomisation until discontinuation of ventilation (for those ventilated), mortality, proportion of participants dead or disabled (unable to walk without aid) after 12 months, improvement in disability grade after six and 12 months, relapse, and adverse events related to corticosteroid treatment. DATA COLLECTION AND ANALYSIS: Two authors extracted the data. MAIN RESULTS: Six trials with 587 participants provided data for our primary outcome measure . The overall evidence showed no significant difference between the corticosteroid and non-corticosteroid treated patients in disability grade. In four trials of oral corticosteroids with 120 participants in total, there was significantly less improvement after four weeks with corticosteroids than without corticosteroids (weighted mean difference of 0.82 of a disability grade less improvement, 95% confidence intervals 0.17 to 1.47). In two trials with a combined total of 467 participants, there was a trend towards more benefit from intravenous corticosteroids which was not quite significant, weighted mean difference 0.17 (95% confidence intervals -0.06 to 0.39) of a disability grade more improvement after four weeks than with placebo. There were no important significant differences between the corticosteroid-treated participants and the control group in any of the secondary outcome measures. Diabetes was significantly more common and hypertension much less common in the corticosteroid-treated participants. AUTHORS' CONCLUSIONS: Limited evidence shows that oral corticosteroids significantly slow recovery from Guillain-Barré syndrome. Substantial evidence shows that intravenous methylprednisolone alone does not produce significant benefit or harm. In combination with intravenous immunoglobulin, intravenous methylprednisolone may hasten recovery but does not significantly affect the long-term outcome. More research is needed and more effective treatments for Guillain-Barré syndrome should be sought.

Intravenous immunoglobulin for Guillain-Barré syndrome.

BACKGROUND: Guillain-Barré syndrome is an acute, paralysing, inflammatory peripheral nerve disease. Intravenous immunoglobulin is beneficial in other autoimmune diseases. OBJECTIVES: We aimed to determine the efficacy of intravenous immunoglobulin for treating Guillain-Barré syndrome. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Trials Register (March 2005), MEDLINE (January 1966 to March 2005) and EMBASE (January 1980 to March 2005) using the terms 'Guillain-Barré syndrome' and 'acute polyradiculoneuritis'. SELECTION CRITERIA: We included all randomised and quasi-randomised trials. DATA COLLECTION AND ANALYSIS: Two authors independently selected papers, extracted data and assessed quality. MAIN RESULTS: Another Cochrane systematic review has shown that plasma exchange significantly hastens recovery. We found six randomised trials comparing intravenous immunoglobulin with plasma exchange. We undertook a meta-analysis of five trials involving 536, mostly adult participants who were unable to walk unaided and had been ill for less than two weeks. Our primary outcome measure was the change in a seven-grade disability scale four weeks after randomisation. The weighted mean difference of this measure was not statistically significant, being only -0.02 (95% confidence interval -0.25 to 0.20) of a disability grade more improvement in the intravenous immunoglobulin than the plasma exchange group. There were no statistically significant differences in other measures. One trial involving 249 participants compared plasma exchange followed by intravenous immunoglobulin with plasma exchange alone. Another involving 37 participants compared immunoabsorption followed by intravenous immunoglobulin with immunoabsorption alone. Neither revealed significant extra benefit from intravenous immunoglobulin. One study with 39 participants showed a trend towards more improvement with high-dose compared with low-dose intravenous immunoglobulin. Another trial with 51 children found no significant difference in outcome when the standard dose was given over two days rather than five days. Three studies including a total of 75 participants suggested that in children intravenous immunoglobulin significantly hastens recovery compared with supportive care. AUTHORS' CONCLUSIONS: In adults, there are no adequate comparisons with placebo. Randomised trials in severe disease show that intravenous immunoglobulin started within two weeks from onset hastens recovery as much as plasma exchange, which is known to be more effective than supportive care. Treatment with intravenous immunoglobulin is significantly more likely to be completed than plasma exchange. Giving intravenous immunoglobulin after plasma exchange did not confer significant extra benefit. In children, intravenous immunoglobulin probably hastens recovery compared with supportive care alone. More research is needed in mild disease and in treatment starting more than two weeks after onset of the condition. Dose-ranging studies are also needed.

Delivery of the posterior arm reduces shoulder dimensions in shoulder dystocia.

OBJECTIVE: To evaluate a possible reduction in shoulder diameter and circumference by extending the posterior arm during delivery, for an easier birth in cases of shoulder dystocia. METHODS: In this study of 33 neonates the bisacromial diameter and axilloacromial circumference were measured within 72 h of birth, first with the neonate's arms by its chest and then with 1 arm extended above its head. Reductions in diameter and circumference were evaluated. RESULTS: The mean +/- SD differences in bisacromial diameter and axilloacromial circumference were 1.9 +/- 0.69 cm and 2.52 +/- 1.18 cm, respectively. A greater reduction was observed in neonates with a greater shoulder diameter. CONCLUSION: In cases of shoulder dystocia, delivery of the posterior arm should significantly reduce shoulder dimensions, especially in larger fetuses, and prevent a need for excessive traction.

A controlled investigation of the cause of chronic idiopathic axonal polyneuropathy.

To investigate the aetiology of chronic idiopathic axonal polyneuropathy (CIAP), 50 consecutive patients were compared with 50 control subjects from the same region. There were 22 patients with painful neuropathy and 28 without pain, 26 with sensory neuropathy and 24 with sensory and motor neuropathy. The typical picture was a gradually progressive sensory or sensory and motor neuropathy. It caused mild or sometimes moderate disability, and reduced the quality of life. There was no evidence that alcohol, venous insufficiency, arterial disease or antibodies to peripheral nerve antigens played a significant part. There was a possible history of peripheral neuropathy in the first or second-degree relatives of six patients and no controls (P = 0.01), and claw toes were present in 12 patients and four controls (P = 0.03). Thirty-two per cent of the patients and 14% of the controls had impaired glucose tolerance or fasting hyperglycaemia but, after adjusting for age and sex, the difference was not significant (P = 0.45), even in the painful neuropathy subgroup. The mean (SD) fasting insulin concentrations were significantly (P = 0.01) higher in the patients [75.9 (44.4) mmol/l] than the controls [47.3 (37.9) mmol/l], and the mean was higher still in the painful neuropathy subgroup [92.2 (37.1) mmol/l] (P < 0.0001). However, insulin resistance as assessed using the homeostasis model assessment formula was not significantly greater in the patients, even in those with pain, than the controls. After adjustment for body mass index as well as age and sex, there was no significant difference in the serum cholesterol concentrations, but there were significantly higher triglyceride concentrations in the patients [mean 1.90 (1.41) mmol/l] than the controls [mean 1.25 (0.79] mmol/l) (P = 0.02). In the patients with painful peripheral neuropathy, the mean triglyceride concentration was 2.37 (1.72), which was even more significantly greater compared with the controls (P = 0.003). In conclusion, CIAP is a heterogeneous condition. A logistic regression analysis identified environmental toxin exposure and hypertriglyceridaemia, but not glucose intolerance or alcohol overuse as significant risk factors that deserve further investigation as possible causes of CIAP.

Risk factors associated with Epstein-Barr virus replication in oral epithelial cells of HIV-infected individuals.

OBJECTIVE: To examine risk factors associated with Epstein-Barr virus (EBV) replication in the oral epithelium of an HIV-infected cohort. DESIGN: Longitudinal study of behavioural, medication and immunological parameters of HIV-1-seropositive outpatients attending a genitourinary clinic. Outcome measure was EBV DNA positivity in curetted oral squames, as detected by in situ hybridization. Logistic regression for repeated observations of the same individuals was used to analyse how risk changed over time. RESULTS: Fifty six individuals were studied; 158 patient-visits were made in total (mean, 2.8). Of 137 samples curetted from the tongue, 36 were positive for EBV DNA. Recreational drug use, oral sexual practices, therapy with zidovudine and aciclovir, and changes in CD4 and total lymphocyte counts were not associated with changes in risk. Alcohol drinking, elevated CD8 lymphocyte counts and fluconazole therapy were associated with a decreased risk, and cigarette smoking with increased risk. CONCLUSION: Behavioural and HIV-specific immunological changes may play important roles in promoting and affecting the course of oral EBV replication. Rigorous anticandidal therapy and avoidance of cigarette smoking may retard the development of oral hairy leukoplakia.

United Kingdom AIDS survival in adults.

OBJECTIVE: To examine the impact of age, year and region of AIDS diagnosis on early (up to 12 months) and late survival of AIDS patients in different exposure categories; to describe the hazard pattern from 12 months after AIDS diagnosis. PATIENTS: A total of 4577 UK adult AIDS diagnoses to the end of 1991 in men who have sex with men, 273 AIDS cases in injecting drug users, 411 AIDS patients infected by blood products, and 535 other adult AIDS cases, mainly ascribed to heterosexual transmission. Deaths have been recorded for 4739 of these 5796 AIDS patients. RESULTS: The influence of calendar year and region of AIDS diagnosis on survival were short-term, for the most part operative only within the first year of follow-up. The monthly death-rate was roughly constant from 12 to 48 months post-AIDS [pooled estimate, 0.055 with 95% confidence interval (CI), 0.053-0.057] but was more than halved for 4-year survivors (pooled estimate, 0.022; 95% CI, 0.017-0.027). About 7% of AIDS cases diagnosed in 1990-1991 survive for at least 48 months. Survival after AIDS diagnosis shortens with advancing age at AIDS diagnosis: the relative hazard per decade of age (1.35; 95% CI, 1.29-1.41 in the first year after AIDS) is significantly greater (P < 0.001) in the first year after AIDS diagnosis than from 12 to 48 months (1.19; 95% CI, 1.13-1.25 in the second epoch). CONCLUSIONS: The influence of covariates, including age, is strongest in the first year of follow-up after AIDS diagnosis. Monthly death-rate is roughly constant at 0.055 from 12 to 48 months post-AIDS and at 0.022 thereafter.

HIV infection in injecting drug users attending centres in England and Wales, 1990-1991.

OBJECTIVE: To monitor trends in HIV infection and associated risk behaviours in injecting drug users (IDU) in England and Wales. DESIGN: Ongoing voluntary unlinked anonymous cross-sectional survey. METHOD: IDU attending centres in 1990 and 1991 were invited to complete a brief questionnaire requesting demographic and behavioural information, and to provide a saliva sample to be tested for antibodies to HIV and to the core antigen of hepatitis B virus (HBV). RESULTS: In 1990, 1.2% (19 out of 1543) of samples from 33 centres, and in 1991 1.8% (25 out of 1417) of samples from 37 centres contained antibody to HIV. Antibody t9 HBV core-antigen was found in 33 and 31% of IDU in 1990 and 1991, respectively. The prevalence of HIV infection in IDU attending centres in London (4.2%) was higher than in those attending centres elsewhere (0.8%). The prevalence of HIV infection in 1991 varied between individual centres from 0 to 10.6%, and at many centres outside London no IDU were infected with HIV. In the same year the prevalence of past infection with HBV varied from 14 to 54%, and IDU who had evidence of HBV infection were found among attenders in nearly all centres. The prevalences of sharing injecting equipment and risky sexual behaviour were high at many centres. The prevalence of HIV infection was higher in IDU who had started to inject in 1985 or earlier, than in those who started injecting later. In each year, approximately half the IDU surveyed reported having had a voluntary confidential HIV-antibody test, and the prevalence of HIV infection was five times higher in those tested than in those who had not been tested. CONCLUSIONS: HIV prevalence in IDU attending centres in England and Wales was low in 1990-1991. There is some indication that IDU have modified their injecting or sexual behaviour, but even at existing reduced levels of risk behaviour, transmission can occur in HIV is introduced into previously unexposed groups.

An assessment of disability rating scales used in multiple sclerosis.

Twenty patients with clinically definite, stable multiple sclerosis were examined independently by three of us at the same visit and given scores on the Ambulation Index, Expanded Disability Status Scale, and Kurtzke Functional System scales. Observer error accounted for 12% to 55% of the variation observed between individual Kurtzke Functional System scores, 17.1% of the variation observed between the patients' Expanded Disability Status Scale scores, and only 3.9% of the variation between Ambulation Index scores. The implications of these findings for the choice of scales in clinical trials are described.

Preceding infections, immune factors, and outcome in Guillain-Barré syndrome.

OBJECTIVE: To test the hypothesis that different preceding infections influence the neurophysiologic classification and clinical features of Guillain-Barré syndrome (GBS). METHODS: We tested pretreatment sera, 7 +/- 3 (mean +/- SD) days from onset, from 229 patients with GBS in a multicenter trial of plasma exchange and immunoglobulin, for serological markers of infection, adhesion molecules, and cytokine receptors, and compared these with neurophysiologic and clinical features. RESULTS: Recent infection by Campylobacter jejuni was found in 53 patients (23%), cytomegalovirus in 19 (8%), and Epstein-Barr virus in four (2%). Patients with C. jejuni infection were more likely than others to have neurophysiologic criteria of axonal neuropathy or inexcitable nerves, antiganglioside GM(1) antibodies, pure motor GBS, lower CSF protein, and worse outcome. Patients with cytomegalovirus infection were younger and more likely than others to have raised serum concentrations of molecules important in T lymphocyte activation and migration, soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble leukocyte selectin, and soluble interleukin-2 receptor (sIL-2R). Concentrations of sICAM-1 and soluble tumor necrosis factor receptor were higher in patients with inexcitable nerves than those with demyelinating neurophysiology. Logistic regression analysis showed death or inability to walk unaided at 48 weeks were associated with diarrhea, inexcitable nerves, severe arm weakness, age over 50, raised sIL-2R concentration and absence of immunoglobulin (Ig) M antiganglioside GM(1) antibodies. CONCLUSIONS: Subtypes of GBS defined by preceding infections were only approximately associated with different patterns of clinical, neurophysiologic, and immunologic features. A single infectious agent caused more than one type of pathology in GBS, implying interaction with additional host factors. Most patients had no identified infection.

When and why children first start to smoke.

Most investigations of smoking in children focus on prevalence in which uptake and maintenance are confounded. This paper reports an analysis of pure incidence data in a cohort of over 6000 Derbyshire schoolchildren followed for ten years investigated using survival data analysis techniques. Over 70% of the cohort tried at least one cigarette before the end of the fifth year of secondary school. Some 40% identified themselves as regular smokers while at school. The risks of taking up regular smoking were higher if, at the age of 11.7-12.7 years, the children had smoking siblings, opposite sex friends, were dismissive of the health hazards and susceptible to peer pressure. More girls than boys in that age range spent time with opposite sex companions and in organized social activities which in turn were significantly associated with the risk of taking up smoking. Thus the earlier physical and emotional development of girls may help explain recent findings that adolescent girls are now more likely to smoke than boys of the same age. The greatest incidence of regular smoking occurred when the average age was increasing from 14.2 to 15.2 years. This has very clear implications for the timing of anti-smoking interventions.

The development of smoking during adolescence--the MRC/Derbyshire Smoking Study.

Each year from 1974, when they entered secondary school, to 1978, when they reached school-leaving age, a cohort of over 6000 schoolchildren from Derbyshire, England, answered a questionnaire about their own and their family's smoking practices and their social activities. Their replies revealed a steady increase in the prevalence of smoking during adolescence. Those children who in 1974 smoked, had friends of the opposite sex, were highly involved in social activities, experienced peer pressure to smoke and rejected the health hazards of smoking were more likely to be regular smokers in 1978 than were other children. Similarly, those children who, when aged 11-12 years, had parents or siblings who smoked, had friends of the opposite sex, and were highly involved in social activities increased their smoking rapidly in subsequent years. Sex and social class differences in the strength of these associations suggest that an understanding of the development of smoking during adolescence requires knowledge of the particular character of the social relationships among different subgroups of that age-group and the various meanings of smoking to them.

An investigation of the role of fathers in immunization uptake.

BACKGROUND: Mothers, but not fathers, are the usual focus of strategies to maximize immunization coverage in low income countries. METHODS: A study of the immunization determinants of children aged 12-18 months was conducted in 1991 in the Eastern Region of Ghana using structured interviews of a population sample of 294 mothers and 170 (67%) of the children's fathers. RESULTS: Fathers were more likely than mothers to perceive that the fathers had participated in the decision to send children for immunizations. Where both parents reported that the father had participated in the decision, and he could speak English, the child was more likely to have completed the immunization schedule by 12 months (OR = 5.7, 95% confidence interval [CI]: 1.5-21.7), independently of other factors. Neither the father's participation, nor his ability to speak English, was independently associated with the child's immunization status. CONCLUSIONS: The results of the study suggest that, where fathers have a higher level of education, programmes which are designed to involve them in decisions about their children's use of preventive health services have the potential to increase timely immunization coverage levels.

PIP: Programs and strategies to maximize immunization coverage in low income countries generally focus upon mothers. 294 mothers of children aged 12-18 months and 170 (67%) of the children's fathers were interviewed in a 1991 study of immunization determinants in the Eastern Region of Ghana. Fathers were more likely than mothers to perceive that the fathers had participated in the decision to send children for immunizations. Where both parents reported the father's involvement in the decision making process, and the father could speak English, the child was more likely to have completed the immunization schedule by 12 months, independently of other factors. Neither the father's participation, nor his ability to speak English, was independently associated with the child's immunization status. These findings suggest that where fathers have a relatively higher level of education, programs involving them in decision making about their children's use of preventive health services may increase timely immunization coverage levels.

An investigation assessing the fraction of human immunodeficiency virus infection attributable to ethnic group variations in risk.

Considerable speculation and a recent publication has suggested that much of the human immunodeficiency virus (HIV-1) infection in the subset of the UK population represented by women having babies in Metropolitan London is substantially imported from Africa. Other data are supportive of this hypothesis. Ades et al. (1992) concluded that the fraction of HIV seroprevalence, identified in a large London-based study using neonatal blood from the dried blood spots on Guthrie cards, attributable to mothers born in Africa was 92.4% with 95% CI: 82-100%. This is an important observation which requires confirmation. This paper reports on an attempt to do this with closely similar methodology using the Unlinked Anonymous Survey (UAS) of HIV-1 seroprevalence in pregnant women attending antenatal centres, together with data from the Office of Population Censuses and Surveys (OPCS) on the country of origins of mothers delivering in 1991 at the 15 London centres included in the UAS. As in Ades' analysis there appeared to be a strong association between centre prevalences and the proportions of women of African origin delivering at those centres. This was consistent with a high fraction of seroprevalence attributable to such women, but it was also clear that the assumptions required for the estimation of the attributable fractions were not fully met. Analyses modified to justify the assumptions produced attributable fraction estimates ranging from 44% to 96% with lower 95% confidence limits 20% or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma of prostate treated by radical external beam radiotherapy using hypofractionation. Twenty-two years' experience (1962-1984).

The survival of 209 patients with apparently localized carcinoma of the prostate treated by radical external beam radiotherapy is reported, noting the influence of age, stage of the disease at presentation, initial histology, previous surgery, and dose of radiotherapy given. From this it is seen that the development of a six-fraction regimen given over a period of three weeks leads to excellent results whether assessed as a local response or by survival curves and to the economical use of scarce resources, but, even more important, is less wearing for patients than conventional daily fractionation and with no major early or late morbidity recorded up to October 1986.

The rate and cost of hospital-acquired infections occurring in patients admitted to selected specialties of a district general hospital in England and the national burden imposed.

Between April 1994 and May 1995 4000 adult patients admitted to selected specialties of a district general hospital were recruited to this study. Hospital-acquired infections presenting during the in-patient stay were identified using previously validated methods of surveillance, and information on daily resource use by both infected and uninfected patients was recorded and estimates of their cost derived. Linear regression modelling techniques were used to estimate how much of the observed variation in resource use and costs could be explained by the presence of an infection. Complete in-patient data sets were obtained for 3980 patients. Of these, 309 patients (7.8%; 95% CI; 7.0, 8.6) presented with one or more hospital-acquired infections during the in-patient period. Infected patients, on average, incurred hospital costs 2.9 (regression model estimate: 2.8; 95% CI; 2.6, 3.0) times higher than uninfected patients, equivalent to an additional pound3154 (regression model estimate pound2917). Both the incidence and the economic impact varied with site of infection and with admission specialty. Estimates of the burden of hospital-acquired infections occurring in adult patients admitted to similar specialties at NHS hospitals in England were derived from the results of this study. An estimated 320 994 (95% CI; 288 071, 353 916) patients per annum acquire one or more infections which present during the in-patient period, and these infections cost the hospital sector an estimated 930.62 million pounds (95% CI; 780.26 pounds; 1080.97 million pounds) per annum. The results presented represent the gross economic benefits that might accrue if these infections are prevented. Further research is required to establish the net benefits of prevention.

Long term effect of a school based antismoking programme.

In the winters of 1977-8 and 1978-9 about 400 children in seven junior schools in northern England were taught the "My Body" health education programme. In the springs of 1980 and of 1982 these children, and an age matched control group, answered a questionnaire about their smoking behaviour, knowledge, and attitudes. Comparison of the two groups suggested that the programme had had a positive effect on the boys but a negligible, or even negative, effect on the girls. Various suggestions as to the reasons for this differential impact are discussed.

School characteristics and adolescent smoking. Results from the MRC/Derbyshire Smoking Study 1974-8 and from a follow up in 1981.

In the MRC/Derbyshire Smoking Study a cohort of about 6000 adolescents was surveyed annually from 1974 when they entered secondary school aged 11-12 years until 1978 when they reached 15-16 years. In 1981 after the adolescents had left school they were again surveyed by post. Each year from 1974 to 1978 and again in 1981 they answered a questionnaire on their smoking behaviour and other issues. Information on the schools attended by these adolescents was obtained from their teachers and headteachers. This paper examines the relation between the school environment and the adolescents' smoking behaviour both before and after leaving school. The prevalence of smoking was higher among those boys who attended schools that were single sex, non-denominational, or had a parent-teacher association, no health education, no female teachers, or whose headteacher smoked cigarettes. Among girls the prevalence of smoking was higher if they attended a school that had optional school uniform and no health or antismoking education. The importance of these findings for the development of effective preventive measures is discussed.

Relation between parents' and children's smoking behaviour and attitudes.

In the MRC/Derbyshire Smoking Study, a cohort of about 6000 adolescents was surveyed annually about their smoking behaviour, attitudes, and other issues from when they entered secondary school at 11-12 until 15-16 years and then again at 18-19 years. Their parents answered a similar questionnaire when their children were aged 11-12 and 15-16 years. In this paper we report the findings of an investigation focussed on the relation between parents' and childrens' smoking behaviour and attitudes at different stages of adolescence. It reveals substantial agreement between children's and parents' reports of parents' smoking behaviour and attitudes, that children from one-parent families are more likely than their peers to smoke, and that boys are more likely to smoke if their fathers smoke and girls if their mothers smoke. In addition, maternal attitudes were independently related to the boys' smoking behaviour. The implications of these findings for health education are discussed.

The Hawthorne effect in the measurement of adolescent smoking.

It is possible that the process of repeatedly measuring the smoking behaviour of adolescents may very well affect that behaviour. This paper reports a test for the extent of such a "Hawthorne" effect in a longitudinal survey of smoking by English adolescents. The self-reported smoking behaviour of 15-16 year olds who attended schools which had participated in the study for five years was compared with that of 15-16 year olds who attended other schools. The prevalence of smoking was lower in those schools which had been surveyed for five years. A number of possible explanations for this finding are discussed. It is concluded that such a "Hawthorne" effect is unlikely to bias analyses relying on comparisons within the data set. However, they can certainly bias the prevalance estimates obtained from such a study. Thus they provide yet another reason why prevalence estimates from cohorts studied over a period of time must be used with considerable caution.