Long-term survival and valve-related complications in young women with cardiac valve replacements

BACKGROUND

The type of cardiac valve replacement associated with the lowest health risks for young women who may undergo pregnancies is unknown. We investigated which valve type was associated with greatest patient and valve survival and the effect of pregnancy on valve loss.

METHODS AND RESULTS

In this retrospective study, all women 12 to 35 years old who underwent valve replacements between 1972 and 1992 at Greenlane Hospital were identified, and follow-up was available in 93%. The 232 women were followed up for 1499 patient-years. Ten-year survival of women with mechanical (n=178), bioprosthetic (n=73), and homograft (n=72) valves was 70% (95% CI, 59% to 83%), 84% (95% CI, 72% to 99%), and 96% (95% CI, 91% to 100%), P=0.002. After adjustment for confounding variables, the relative risk (RR) of death with mechanical compared with bioprosthetic valves was 2.17 (95% CI, 0.78 to 5.88). Thromboembolic events occurred in 45% of women with mechanical valves within 5 years, compared with 13% with bioprosthetic valves, P=0.0001. Valve loss at 10 years was higher in bioprosthetic valves [82% (95% CI, 62% to 92%)] than in mechanical [29% (95% CI, 17% to 39%)] or homograft [28% (95% CI, 12% to 41%)] valves, P=0.0001. Pregnancy was not associated with increased bioprosthetic (RR, 0.96; 95% CI, 0.68 to 1. 35), homograft (RR, 0.65; 95% CI, 0.37 to 1.13), or mechanical (RR, 0.54; 95% CI, 0.27 to 1.08) valve loss.

CONCLUSIONS

Although 10-year valve survival was greater with mechanical than bioprosthetic valves, mechanical valves may be associated with reduced patient survival in young women. Thromboembolic complications, often with long-term sequelae, were common with mechanical valves. Pregnancy did not increase structural deterioration or reduce survival of bioprosthetic valves.

Effect of preoperative paracetamol on gastric volumes and pH in children

The effect preoperative paracetamol elixir has on gastric contents is unknown. Children presenting for elective adenotonsillectomy were randomized to receive either paracetamol elixir (40 mg x kg(-1)) 90 min before surgery or paracetamol suppositories (40 mg x kg(-1)) intraoperatively. Following induction of anaesthesia a 16 Fr multiple-oriface orogastric tube was passed into the stomach and measure taken of the residual gastric volume and pH. The children had a mean age of 8.5 years (SD 3.2) with a weight of 35 kg (SD 16.5). Children given elixir (n=41) had a mean residual gastric volume of 0.083 ml x kg(-1) (95% CI; 0.006, 1.24) and a pH of 1.83 (95% CI; 0.75, 4.49), while those given suppositories (n=40) had a mean residual gastric volume of 0.083 ml x kg(-1)(95% CI; 0.008, 0.9) and a pH of 2.07 (95% CI; 0.84, 5.12). There was no significant difference between these two groups. Paracetamol elixir is rapidly absorbed in the gastrointestinal system of children and preoperative administration has no effect on gastric contents. Given paracetamol's slow equilibration rate constant from the central to the effect compartment, children may be given this medication preoperatively for routine surgical procedures.

Seasonal differences in risk factors for sudden infant death syndrome. The New Zealand Cot Death Study Group

The aim of this study was to explore whether the risk of sudden infant death syndrome (SIDS) associated with prone sleeping position and other risk factors varies with season. The study was a large nation-wide case-control study, which compared 485 cases with 1800 controls. Parents of 393 (81.0%) cases and 1591 (88.4%) controls were interviewed. Obstetric records were also examined. Infants dying in winter were older and had lower birthweights than those dying in summer. The increased risk of SIDS associated with prone sleeping position was greater in winter than in summer. In contrast, the increased risk of SIDS associated with excess thermal insulation and bed sharing was less in winter than in summer. Prone sleeping position accounts for about half of the difference between the mortality rate in summer and that in winter. This suggests that some factor related to season modifies the effect of prone sleeping position.

Risk factors for preterm birth: a New Zealand study

AIM

To identify risk factors for preterm birth.

METHODS

A cross sectional study. The study population was 1800 infants selected randomly from all babies born over a three-year period. Of these, 85 (4.8%) were classified preterm (less than 37 completed weeks gestation). Data were collected from obstetric records and parental interviews.

RESULTS

Risk factors associated with an increased risk of preterm birth after controlling for potential confounders included smoking during pregnancy (adjusted relative risk (RR) = 2.7, 95% confidence interval (CI) = 1.3, 5.4), and multiple birth (adjusted RR = 48.8, 95% CI = 18.1, 131.4). Urinary tract infection was significant at the 7% level (adjusted RR = 2.3, 95% CI = 1.0, 5.6). Alcohol intake in third trimester was associated with a reduced risk of preterm birth (adjusted RR = 0.4, 95% CI = 0.2, 0.7).

CONCLUSION

Maternal smoking and multiple births were the most important modifiable risk factors in this study for preterm birth and may contribute to 17% and 11% of preterm births respectively.

Heavy caffeine intake in pregnancy and sudden infant death syndrome. New Zealand Cot Death Study Group

AIMS

To examine the association between maternal caffeine consumption during pregnancy and the risk of sudden infant death syndrome (SIDS).

METHODS

A nationwide case-control study surveying parents of 393 SIDS victims and parents of 1592 control infants. Caffeine consumption in each of the first and third trimesters was estimated by questionnaire. Heavy caffeine intake was defined as 400 mg/day or more (equivalent to four or more cups of coffee per day).

RESULTS

Infants whose mothers had heavy caffeine consumption throughout their pregnancy had a significantly increased risk for SIDS (odds ratio 1.65; 95% confidence interval 1.15 to 2.35) after adjusting for likely confounding factors.

CONCLUSION

Caffeine intake has been associated with fetal harm and now SIDS. Reducing heavy caffeine intake during pregnancy could be another way to lessen the risk of SIDS. This needs confirmation by others.

Risk factors for sudden infant death syndrome following the prevention campaign in New Zealand: a prospective study

OBJECTIVES

To identify the risk factors for sudden infant death syndrome (SIDS) following a national campaign to prevent SIDS.

METHODS

For 2 years (October 1, 1991 through September 30, 1993) data were collected by community child health nurses on all infants born in New Zealand at initial contact and at 2 months.

RESULTS

There were 232 SIDS cases in the postneonatal age group (2.0/1000 live births) and these were compared with 1200 randomly selected control subjects. Information was available for 127 cases (54.7%) and 922 (76.8%) of controls. The previously identified modifiable risk factors were examined. The prevalence of prone sleeping position of the infant was very low (0.7% at initial contact and 3. 0% at 2 months), but was still associated with an increased risk of SIDS. In addition, the side sleeping position was also found to have an increased risk of SIDS compared with the supine sleeping position (at 2 months: adjusted odds ratio (OR) = 6.57; 95% confidence interval (CI) = 1.71, 25.23). Maternal smoking was found to be the major risk factor for SIDS. Bed sharing was also associated with an increased risk of SIDS. There was an interaction between maternal smoking and bed sharing on the risk of SIDS. Compared with infants not exposed to either bed sharing or maternal smoking, the adjusted OR for infants of mothers who smoked was 5.01 (95% CI = 2.01, 12.46) for bed sharing at the initial contact and 5.02 (95% CI = 1.05, 24. 05) for bed sharing at 2 months. In this study breastfeeding was not associated with a statistically significant reduction in the risk of SIDS. The other risk factors for SIDS identified were: unmarried mother, leaving school at a younger age, young mother, greater number of previous pregnancies, late attendance for antenatal care, smoking in pregnancy, male infant, Maori ethnicity, low birth weight, and shorter gestation.

CONCLUSIONS

After adjustment for potential confounders, prone and side sleeping positions, maternal smoking, and the joint exposure to bed sharing and maternal smoking were associated with statistically significant increased risk of SIDS. A change from the side to the supine sleeping position could result in a substantial reduction in SIDS. Maternal smoking is common in New Zealand and with the reduction in the prevalence of prone sleeping position is now the major risk factor in this country. However, smoking behavior has been difficult to change. Bed sharing is also a major factor but appears only to be a risk to infants of mothers who smoke. Addressing bed sharing among mothers who smoke could reduce SIDS by at least one third. Breastfeeding did not appear to offer a statistically significant reduction in SIDS risk after adjustment of potential confounders, but as breastfeeding rates are comparatively good in New Zealand, this result should be interpreted with caution as the power of this study to detect a benefit is small.

An ageing-associated decline in force production after repetitive contractions by rat skinned skeletal muscle fibres

Chemically skinned muscle fibre segments were prepared from the extensor digitorum longus (EDL) and soleus muscles of young (5-6 months) and old (24-31 months) male Wistar rats. Muscle fibres were activated repetitively with a buffered calcium solution a total of 50 times, and the force resulting from each activation recorded. Both EDL and soleus fibres showed a substantial decline in maximum force over the series of 50 contractions. The decline in maximum force was significantly higher in old EDL and soleus fibres than in their young counterparts, indicating a difference between the contractile apparatus of skeletal muscle from young and old animals. Normalized tension, defined as force per muscle fibre cross-sectional area, was significantly lower in fibres from the old animals than from the young, giving further evidence of the existence of changes to the contractile apparatus with ageing.

Gender and the sudden infant death syndrome. New Zealand Cot Death Study Group

A nationwide case-control study compared the prevalence and magnitude of risk factors for sudden infant death syndrome (SIDS) in male and female infants. The risk factors of SIDS and their magnitude for males and females are very similar. After adjustment for potential confounders male infants had a 1.42-fold (95% CI = 1.04, 1.94) increased risk of SIDS compared with females. Risk factors identified in most epidemiological studies are not the reason for the increased SIDS mortality seen in male infants.

SIDS, illness, and acute medical care. New Zealand Cot Death Study Group

One component of the Back to Sleep campaign to reduce the risk of sudden infant death syndrome (SIDS) is the recommendation that parents seek medical attention if their infant is unwell. The aim of this study was to investigate of SIDS could in part be explained by sick infants not getting appropriate medical care. Data on symptoms of illness and on acute medical contacts made for infants dying from SIDS (n = 390) within two weeks of their death were compared with those from a randomly selected group of control infants (n = 1592). SIDS cases had more severe illness than controls (odds ratio (OR) = 3.43; 95% confidence interval (CI) = 1.69 to 5.38), and were more likely to have seen a general practitioner (OR = 1.37; 95% CI = 1.09 to 1.73) or attended hospital (OR = 3.43, 95% CI = 1.09 to 1.73). Only 1.3% of all SIDS cases had symptoms suggesting severe illness and had not seen a general practitioner. A lack of medical contacts in the two weeks before death does not contribute to the risk of SIDS.

Declining rates of coronary heart disease in New Zealand and Australia, 1983-1993

The authors report the results of 10 years of monitoring of trends in the rates of major nonfatal and fatal coronary events and in case fatality in Auckland, New Zealand, and in Newcastle and Perth, Australia. Continuous surveillance of all suspected myocardial infarctions and coronary deaths in people aged 35-64 years was undertaken in the three centers as part of the World Health Organization's Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) Project. For nonfatal definite myocardial infarction, there were statistically significant declines in rates in all centers in both men and women, with estimated average changes between 2.5% and 3.7% per year during the period 1984-1993. Rates of all coronary deaths also declined significantly in all three populations for both men and women. In absolute terms, there was, in general, a greater reduction in prehospital deaths than in deaths after hospitalization. Although 28-day case fatality remains high at between 35% and 50%, in the Australian centers it declined significantly by between 1.0% and 2.9% per year, and in Auckland there was also a small decline. However, since most deaths occur outside the hospital in people without a previous history of coronary heart disease, an increased emphasis on primary prevention is necessary.

The effect of season-of-response to ISAAC questions about asthma, rhinitis and eczema in children

BACKGROUND

To examine whether responses to questions about the lifetime prevalence and 12-month period prevalence of symptoms of asthma and allergies are affected by the season in which the questions are asked.

METHODS

The international Study of Asthma and Allergies in Childhood (ISAAC) Phase One was undertaken in six New Zealand centres; in three centres the effect of season was studied. Over three school terms at least 3000 children were studied in each of two age groups per centre (6-7 years; 13-14 years), one-third in each term respectively. The ISAAC standardized written questionnaires were used to identify asthma, rhinitis and eczema symptoms. The written questionnaire in the younger age group was completed by the parent/guardian. The older age group self-completed the written questionnaire and also a video questionnaire about asthma symptoms.

RESULTS

The total number of respondents was 21,437, approximately half in each age group. The season of responding had no effect on the level of response to eczema questions. For the written asthma questionnaire no season-of-response effect was present for 6-7 year olds; for 13-14 year olds there was a trend to a higher rate of positive responses by those responding in winter, but in only one question did this reach statistical significance. With the video questionnaire there was a similar trend for a higher rate of positive responses when questions were asked in winter, but this did not reach statistical significance. For rhinitis symptoms there was a statistically significant season-of-response effect in both age groups with two questions; the fewest positive responses by the winter responders.

CONCLUSIONS

There was no significant effect of season-of-response to questions on eczema symptoms, and most questions on asthma symptoms. There was a season-of-response effect on responses to questions on rhinitis symptoms suggesting a recall bias relating to recency of symptoms.

Measuring morbidity from asthma in children

AIMS

To develop new measures of asthma morbidity which would be applicable to children with asthma of all grades of severity.

METHODS

This study used a cross sectional sample of asthmatic children. Traditional asthma morbidity measures (admission to hospital, use of Emergency Room, general practitioner, after hours deputising service and ambulance) were compared with new measures (school attendance, teacher assessment, parental perception of morbidity and parents emotional response to child's asthma).

RESULTS

Data was obtained for 381 children with asthma. Children with poor school attendance were found in the severe group as judged by a composite score using traditional measures (r = 0.30, p < 0.0001). A new composite morbidity score based on two questions about parental perception of severity (how often has asthma prevented participation in activities and rating of severity of asthma in general over the last year) and two questions about parent emotional response to the child's asthma (how often has your child's asthma (a) made you feel frightened and (b) stopped family activities) was developed. This new measure of asthma morbidity was correlated with the composite score using traditional morbidity measures (r = 0.43, p < 0.0001) and with school attendance (r = 0.28, p < 0.0001).

CONCLUSION

These new morbidity measures are quick and easy to use, and provide an opportunity to measure asthma severity at the moderate to mild end of the severity spectrum. We recommend their use for both clinical assessment and research.

Sex differences in case fatality before and after admission to hospital after acute cardiac events: analysis of community based coronary heart disease register

OBJECTIVE

To determine whether the reported higher case fatality in hospital after an acute cardiac event in women can be explained by sex differences in mortality before admission and in baseline risk factors.

DESIGN

Analyses of data from a community based coronary heart disease register.

SETTING

Auckland region, New Zealand.

SUBJECTS

5106 patients aged 25-64 years with an acute cardiac event leading to coronary death or definite myocardial infarction within 28 days of onset, occurring between 1986 and 1992.

MAIN OUTCOME MEASURES

Case fatality before admission, 28 day case fatality for patients in hospital, and total case fatality after an acute cardiac event.

RESULTS

Despite a more unfavourable risk profile women tended to have lower case fatality before admission than men (crude odds ratio 0.88; 95% confidence interval 0.77 to 1.02). Adjustment for age, living arrangements, smoking, medical history, and treatment increased the effect of sex (0.72; 0.60 to 0.86). After admission to hospital, women had a higher case fatality than men (1.76; 1.43 to 2.17), but after adjustment for confounders this was reduced to 1.18 (0.89 to 1.58). Total case fatality 28 days after an acute cardiac event showed no significant difference between men and women (0.85; 0.70 to 1.02)

CONCLUSIONS

The higher case fatality after an acute cardiac event in women admitted to hospital is largely explained by differences in living status, history, and medical treatment and is balanced by a lower case fatality before admission.

Life events, social support and the risk of sudden infant death syndrome

The effects of a lack of maternal social support and stressful life events on the risk of Sudden Infant Death Syndrome (SIDS) were examined by case-control design: 390 cases and 1592 control infants. A seven item index of mother's social support was used. A possible 21 life events experienced by each family were summed and then put into one of three categories: 0-2, 3-5, and 6 or more life events. Similar levels of maternal social support were found for both groups. SIDS families experienced significantly more stressful life events than control families, but once social factors had been taken into account this association was lost.

A population based strategy to prevent insulin-dependent diabetes using nicotinamide

It has been postulated that treatment with nicotinamide may prevent or delay the onset of insulin dependent diabetes mellitus. We report the findings of a population based diabetes prevention trial which tests this hypothesis. 33,658 school children aged 5-7.9 years were randomly selected (by school) from a total population of 81,993 of such children in the Auckland (New Zealand) region. They were offered testing for islet cell antibodies. 20,195 (60%) consented to testing. Of these 185 had islet cell antibodies and met the criteria for treatment with nicotinamide. 173 received this treatment. The study population has an average follow up time of 7.1 years. The diabetes incidence of the untested controls was: 16.07 (12.4-20.5 95% CI) /100,000 person years at risk; in the group who were tested and treated when deemed appropriate: 7.14 (3.1-14.1 95% CI); and in the group offered testing but who did not consent ("refusers'): 18.48 (10.1-31.0 95% CI). The tested group had a rate of diabetes of 41% (20-85 95% CI) of the other groups combined after an age adjustment, which is significant (p = 0.008). The tested group combined with the "refuser' group (i.e. "intention to treat') also has a lower incidence than the control group (p = 0.12). Nicotinamide has a protective effect against the development of insulin dependent diabetes in this setting but the size of the effect has a wide confidence interval. Further follow up may define the magnitude of the protective effect within narrower limits.

Temperature and the sudden infant death syndrome

The relationship between the days on which sudden infant death syndrome (SIDS) occurred and daily minimum and average temperature was examined for five regions of New Zealand for a three-year period beginning on 1st November 1987. There was a marked winter excess of SIDS. After adjusting for season the temperature on the days preceding SIDS deaths were negatively associated with SIDS, but the effect was not statistically significant. Further analysis, using data from the New Zealand Cot Death Study, a nation-wide case-control study was based on the mean temperature 2 to 5 days before death for the cases or a nominated day for the controls. Statistically significant interaction effects between temperature and sleep position, and temperature and the age of the infant were found. A mean temperature 2-5 days beforehand 2.5 degrees C below that on the day of death or the nominated day increased the risk of SIDS in those sleeping prone by 1.17 [95% CI 0.95 to 1.43] and in those sleeping on their side or back by 0.96 [95% CI 0.77 to 1.19]. In the same circumstances the odds ratio (OR) for infants aged 3 months or less would increase by 0.98 [95% CI 0.80 to 1.19] and that for infants older than 3 months by 1.20 [95 CI 0.97 to 1.49]. The statistically significant negative association between temperature a few days before death and SIDS has been reported previously. Most of the effect of temperature can be attributed to seasonal variations, and minor fluctuations in day to day temperatures make only a very small contribution to SIDS.

Infant room-sharing and prone sleep position in sudden infant death syndrome. New Zealand Cot Death Study Group

BACKGROUND

There is evidence that the risk of sudden infant death syndrome is lower among ethnic groups in which parents generally share a room with the infant for sleeping. We investigated whether the presence of other family members in the infant's sleeping room affects the risk of the sudden infant death syndrome.

METHODS

The case-control study covered a region with 78% of all births in New Zealand during 1987-90. Home interviews were completed with parents of 393 (81.0% of total) babies who died from the sudden infant death syndrome aged 28 days to 1 year and 1592 (88.4% of total) controls, selected from all hospital births in the study region.

FINDINGS

The relative risk of sudden infant death for sharing the room with one or more adults compared with not sharing was 0.19 (95% CI 0.08-0.45) for sharing at night during the last 2 weeks and 0.27 (0.17-0.41) for sharing in the last sleep, after control for other confounders. Sharing the room with one or more children did not affect the relative risk (1.25 [0.86-1.82] for sharing during last 2 weeks; 1.29 [0.85-1.94] for sharing in last sleep). There was a significant interaction (p = 0.033) between not sharing the room with an adult and prone sleep position in the last sleep. Compared with infants sharing the room with an adult and not prone, the multivariate relative risk was 16.99 (10.43-27.69) for infants not sharing with an adult and prone, 3.28 (2.06-5.23) for infants sharing the room and prone, and 2.60 (1.58-4.30) for infants not sharing the room and not prone. The interaction between adult room-sharing and prone sleep position suggests that both exposures may affect the risk of sudden infant death syndrome through a common mechanism.

INTERPRETATION

We recommend that infants sleep in the same bedroom as their parents at night to reduce the risk of sudden infant death syndrome.

Immunisation and the sudden infant death syndrome. New Zealand Cot Death Study Group

AIMS

To examine the relation between immunisation and the risk of sudden infant death syndrome (SIDS).

METHODS

A large nationwide case-control study. Parental held records were used to measure immunisation status.

RESULTS

Infants were at increased risk of SIDS if they had not received the 6 week, 3 month, and 5 month immunisations. After controlling for potential confounding variables, including those which measured health care use and infant illness, the relative risk of SIDS for infants not being immunised at 6 weeks was 2.1 (95% confidence interval = 1.2, 3.5). Four percent of cases died within four days of immunisation and 7.6% of control infants had been immunised within four days of the nominated date. There was a reduced chance of SIDS in the four days immediately following immunisation (OR = 0.5; 95% CI = 0.2 to 0.9).

CONCLUSIONS

Immunisation does not increase the risk of SIDS and may even lower the risk.

Are nappy sterilisers associated with SIDS? New Zealand Cot Death Study Group

Chemicals used to clean nappies have been suggested as a cause of sudden infant death syndrome (SIDS). Parents of 393 cases and 1592 controls were questioned about nappy cleaning procedures. Soaking in sterilisers followed by rinsing in water had a relative risk of 0.91 compared with other cleaning procedures. Nappy cleaning methods are not related to SIDS.

Public health policy on bed sharing and smoking in the sudden infant death syndrome

AIMS

Further develop New Zealand public health policy on infant bed sharing by quantifying the number of sudden infant death syndrome (SIDS) cases attributable to bed sharing among infants of smoking and nonsmoking mothers.

METHODS

A large nation-wide case control study covering a region with 78% of all births in New Zealand during 1987-90. Interviews were completed with parents of 393 (81.0% of total) cases who died from the sudden infant death syndrome in the postneonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region.

RESULTS

The proportion of control infants who usually bed shared in the last 2 weeks was 65.7% in Maori, 73.7% in Pacific Island people and 35.5% in Europeans (44.5% in all ethnic groups combined, and half of these for less than 2 hours per night). There was an interaction between maternal smoking and infant bed sharing on the risk of sudden infant death separately in Maori, Pacific Island and European infants with the risk being highest in infants exposed to both risk factors. 26% of SIDS deaths were explained by bed sharing among infants of smoking mothers (who comprised 16% of the total infant population) and 3% by bed sharing among infants of non-smoking mothers (28% of total infant population).

CONCLUSION

Infant bed sharing is common. The majority of SIDS deaths that are attributed to be sharing occur among infants of smoking mothers. A policy which advises all infants not to bed share is estimated to potentially save an extra 3% of SIDS compared to a policy targeted only on infants of smoking mothers. If public attitudes are favorable to bed sharing, there could be a marginal cost (against its acceptance) by including infants of non-smoking mothers in the recommendation not to bed share. These findings should not be interpreted as indicating that bed sharing where the mother is a nonsmoker is safe or protective against SIDS.

International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods

The aetiology of asthma and allergic disease remains poorly understood, despite considerable research. The International Study of Asthma and Allergies in Childhood (ISAAC), was founded to maximize the value of epidemiological research into asthma and allergic disease, by establishing a standardized methodology and facilitating international collaboration. Its specific aims are: 1) to describe the prevalence and severity of asthma, rhinitis and eczema in children living in different centres, and to make comparisons within and between countries; 2) to obtain baseline measures for assessment of future trends in the prevalence and severity of these diseases; and 3) to provide a framework for further aetiological research into genetic, lifestyle, environmental, and medical care factors affecting these diseases. The ISAAC design comprises three phases. Phase 1 uses core questionnaires designed to assess the prevalence and severity of asthma and allergic disease in defined populations. Phase 2 will investigate possible aetiological factors, particularly those suggested by the findings of Phase 1. Phase 3 will be a repetition of Phase 1 to assess trends in prevalence.

Smoking prevention: attitudes and activities of New Zealand dentists

This study surveyed 400 dentists to determine their current practices with patients who smoke. Although dentists are aware of the importance of counselling patients on the cessation of smoking, they need to take a more active role in these activities. Current evidence suggests that even brief counselling interventions can help some patients stop smoking.

Sudden infant death syndrome in New Zealand: are risk scores useful? New Zealand National Cot Death Study Group

STUDY OBJECTIVE

To evaluate the Christchurch, Invercargill, Dunedin (CID) and Oxford record linkage study (ORLS) risk scores in five regions of New Zealand and examine the effect of risk factors for sudden infant death syndrome (SIDS), such as prone sleeping position, maternal smoking, breast feeding, measures of illness, the use of antenatal classes, community health care, and medical services on a high and low risk group delineated by the CID score.

DESIGN

This was a case-control study of infants dying of SIDS.

SETTING

Both the cases and controls were born in one of five health districts in New Zealand and their parents were interviewed between 1 November 1987 and 31 October 1990.

PARTICIPANTS

The cases were 485 infants who died of SIDS. The controls were a random sample drawn from the same five regions in which the cases were born, chosen so that their age on the day on which they were interviewed was similar to the age at death of the cases. Risk scores were calculated for 387 case and 1579 controls.

MEASUREMENTS AND MAIN RESULTS

Using the recommended cut off points the sensitivity and specificity of the CID and ORLS were found to be similar to those described for other samples. The differences among the regions were significant. There was, however, no evidence that the association between SIDS and the risk factors considered was different in the high and low risk groups delineated by the CID score. The relative attributable risk for smoking was 32.3% in the high risk group. The excess risk that could be attributed to a different prevalence of any of the other risk factors in the high risk group was small when compared with the low risk group.

CONCLUSIONS

Health care resources should be spent on promoting and evaluating good child care practices for all, rather than identifying and promoting special interventions for those in the high risk category.

Factors adversely associated with breast feeding in New Zealand

Control data from 1529 infants studied in a multicentre case-control study of sudden infant death in New Zealand were analysed to identify factors that might hinder the establishment and duration of breast feeding. Although 1300 infants (85%) were exclusively breast-fed at discharge from the obstetric hospital, this fell to 940 (61%) by 4 weeks. Logistic regression was used to identify factors that might adversely influence breast feeding 'at discharge', 'at 4 weeks' and the overall 'duration' of breast feeding. When adjusted for confounding factors, not exclusive breast feeding 'at discharge' was significantly associated with: twin pregnancy, being a Pacific Islander, mother not bedsharing, subsequent dummy use, birthweight less than 2500 g, heavy maternal smoking, not attending antenatal classes and mother less than 20 years old at first pregnancy. Mothers smoking more than 20 cigarettes a day were nearly twice as likely to not exclusively breast feed on discharge compared to those who did not smoke. A 'dose response' was apparent with the heaviest smokers having the least likelihood of establishing exclusive breast feeding. Being exclusively breast-fed at discharge but not 'at 4 weeks' was associated with: twin pregnancy, admission to a neonatal intensive care unit, subsequent dummy use and not being married. A shorter overall 'duration' of breast feeding was associated with maternal smoking, subsequent dummy use, mother not bedsharing, twin pregnancy, mother less than 20 years old at first pregnancy, low occupational status and not attending antenatal classes. These effects persisted when social and demographic factors, including birthweight, were taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)

Travel and changes in routine do not increase the risk of sudden infant death syndrome

We investigated the relationship between travel and changes in routine and the sudden infant death syndrome (SIDS) among 485 SIDS cases compared with 1800 randomly selected control infants. There was no increased risk of SIDS with travel. Special events, such as christenings, were not associated with an increased risk of SIDS. However, visits to and by friends or relatives were associated with a significantly reduced risk of SIDS after controlling for potential confounders (odds ratios = 0.70; 95% confidence interval = 0.52, 0.96). These findings may indicate less social support in SIDS cases.

Bed sharing, smoking, and alcohol in the sudden infant death syndrome. New Zealand Cot Death Study Group

OBJECTIVES

To investigate why sharing the bed with an infant is a not consistent risk factor for the sudden infant death syndrome in ethnic subgroups in New Zealand and to see if the risk of sudden infant death associated with this practice is related to other factors, particularly maternal smoking and alcohol consumption.

DESIGN

Nationwide case-control study.

SETTING

Region of New Zealand with 78% of all births during 1987-90.

SUBJECTS

Home interviews were completed with parents of 393 (81.0% of total) infants who died from the sudden infant death syndrome in the postneonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region.

RESULTS

Maternal smoking interacted with infant bed sharing on the risk of sudden infant death. Compared with infants not exposed to either risk factor, the relative risk for infants of mothers who smoked was 3.94 (95% confidence interval 2.47 to 6.27) for bed sharing in the last two weeks and 4.55 (2.63 to 7.88) for bed sharing in the last sleep, after other confounders were controlled for. The results for infants of non-smoking mothers were inconsistent with the relative risk being significantly increased for usual bed sharing in the last two weeks (1.73; 1.11 to 2.70) but not for bed sharing in the last sleep (0.98; 0.44 to 2.18). Neither maternal alcohol consumption nor the thermal resistance of the infant's clothing and bedding interacted with bed sharing to increase the risk of sudden infant death, and alcohol was not a risk factor by itself.

CONCLUSION

Infant bed sharing is associated with a significantly raised risk of the sudden infant death syndrome, particularly among infants of mothers who smoke. The interaction between maternal smoking and bed sharing suggests that a mechanism involving passive smoking, rather than the previously proposed mechanisms of overlaying and hyperthermia, increases the risk of sudden infant death from bed sharing.

Breastfeeding and the risk of sudden infant death syndrome

The New Zealand Cot Death Study, a multicentre case-control study, was set up to identify risk factors associated with sudden infant death syndrome (SIDS). In the 3 years of the study there were 485 infant deaths classified as SIDS in the study areas and 1800 infants who were randomly selected as controls. Data were collected by parent interviews and from obstetric notes. A full set of data for this analysis was available from 356 cases and 1529 control infants. The relationship between length of any breastfeeding and SIDS was examined: 92% of the controls were initially breastfed compared to 86% of the cases. As time went by, cases stopped breastfeeding sooner than controls: by 13 weeks, 67% controls were breastfed versus 49% cases. A reduced risk for SIDS in breastfed infants persisted during the first 6 months after controlling for confounding demographic, maternal and infant factors. Infants exclusively breastfed 'at discharge from the obstetric hospital' (odds ratio [OR] = 0.52, 95% confidence interval (CI): 0.35-0.71) and during the last 2 days (OR = 0.65, 95% CI: 0.46-0.91) had a significantly lower risk of SIDS than infants not breastfed after controlling for potential confounders. We have shown a substantial association of breastfeeding with a lowered risk for SIDS. This supports the need for more positive promotion and active community support to further enhance the level and length of exclusive breastfeeding.

Smoking and the sudden infant death syndrome

OBJECTIVE

Maternal smoking has been shown to be a risk factor for sudden infant death syndrome (SIDS). The effect of smoking by the father and other household members has not previously been examined.

METHODS

A large nationwide case-control study. Four hundred eighty-five SIDS deaths in the postneonatal age group were compared with 1800 control infants.

RESULTS

Infants of mothers who smoked during pregnancy had a 4.09 (95% confidence interval [CI] = 3.28, 5.11) greater risk of death than infants of mothers who did not smoke. Infants of mothers who smoked postnatally also had an increased risk of SIDS compared with infants of nonsmokers and, furthermore, the risk increased with increasing levels of maternal smoking. Smoking by the father and other household members increased the risk (odds ratio [OR] = 2.41, 95% CI = 1.92, 3.02 and OR = 1.54, 95% CI = 1.20, 1.99, respectively). Smoking by the father increased the risk of SIDS if the mother smoked, but had no effect if she did not smoke. In analyses controlled for a wide range of potential confounders, smoking by the mother and father was still significantly associated with an increased risk of SIDS.

CONCLUSION

Passive tobacco smoking is causally related to SIDS.

Dummies and the sudden infant death syndrome

The association between dummy use and sudden infant death syndrome (SIDS) was investigated in 485 deaths due to SIDS in the postneonatal age group and compared with 1800 control infants. Parental interviews were completed in 87% of subjects. The prevalence of dummy use in New Zealand is low and varies within New Zealand. Dummy use in the two week period before death was less in cases of SIDS than in the last two weeks for controls (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.57 to 1.02). Use of a dummy in the last sleep for cases of SIDS or in the nominated sleep for controls was significantly less in cases than controls (OR 0.44, 95% CI 0.26 to 0.73). The OR changed very little after controlling for a wide range of potential confounders. It is concluded that dummy use may protect against SIDS, but this observation needs to be repeated before dummies can be recommended for this purpose. If dummy sucking is protective then it is one of several factors that may explain the higher mortality from SIDS in New Zealand than in other countries, and may also explain in part the regional variation within New Zealand.

Ethnic differences in mortality from sudden infant death syndrome in New Zealand

OBJECTIVES

To examine the factors which might explain the higher mortality from sudden infant death syndrome in Maori infants (7.4/1000 live births in 1986 compared with 3.6 in non-Maori children).

DESIGN

A large nationwide case control study.

SETTING

New Zealand. 485 infants who died of sudden infant death syndrome were compared with 1800 control infants. There were 229 Maori and 240 non-Maori cases of sudden infant death syndrome (16 cases unassigned) and 353 Maori and 1410 non-Maori controls (37 unassigned).

RESULTS

Maori infants had 3.81 times the risk (95% confidence interval 3.06 to 4.76) of sudden infant death syndrome compared with non-Maori infants. The risk factors for sudden infant death syndrome within groups were remarkably similar. When Maori and non-Maori controls were compared the prevalence of many of the known risk factors was higher in Maori infants. In particular, mothers were socioeconomically disadvantaged, younger, and more likely to smoke and their infants were of lower birth weight and more likely to share a bed with another person. Multivariate analysis controlling for potential confounders found that simply being Maori increased the risk of sudden infant death syndrome by only 1.37 (95% CI = 0.95 to 2.01), not statistically significantly different from 1. Population attributable risk was calculated for prone sleeping position, maternal smoking, not breast feeding, and infants sharing a bed with another person. In total these four risk factors accounted for 89% of deaths from sudden infant death syndrome in Maori infants and 79% in non-Maori infants.

CONCLUSION

The high rate of sudden infant death syndrome among Maori infants is based largely on the high prevalence in the Maori population of the major risk factors. Other risk factors, not related to ethnicity, probably explain remaining differences between Maori and non-Maori children.

Antihypertensive drug effects on placental flow velocity waveforms in pregnant women with severe hypertension

Doppler studies of the uterine and umbilical arteries were performed in 24 acutely hypertensive pregnant women. Women were divided into 2 groups: Group 1 (diastolic blood pressure (DBP) > 110 mm Hg) received placebo (n = 6) or 10 mg oral nifedipine (n = 9); Group 2 (DBP > or = 110 mm Hg) received 10 mg oral nifedipine (n = 5) or 10 mg intravenous hydralazine (n = 4). Treatment allocations were random within groups and the investigator and patient were blind to the treatments. Baseline flow velocity waveforms (FVW) and posttreatment FVW's at 30, 60 and 120 minutes were recorded. There was no significant difference between baseline and posttreatment FVW indices within or between groups. Placebo was as effective as nifedipine in lowering blood pressure over 2 hours of study. There were no significant adverse effects of treatment.

Postnatal depression and SIDS: a prospective study

This study was carried out in response to reports from nurses to a post-neonatal mortality review committee that a number of mothers of infants dying from sudden infant death syndrome (SIDS) appeared to be depressed before the child's death. The New Zealand Cot Death Study was a 3 year multicentre case-control study for SIDS. There were 485 SIDS cases in the post-neonatal age group in the study regions, and these were compared with 1800 control infants. Infants of mothers with either a self-reported use of medication for psychiatric disorders, a history of hospitalization for psychiatric illness or a family history of postnatal depression had a significantly increased risk of SIDS compared with infants of mothers who were either not using medication (odds ratio (OR) = 1.45; 95% confidence interval (CI) = 1.03, 2.04) or were without a history of hospitalization for psychiatric illness (OR = 1.80; 95% CI = 1.03, 3.11) or a family history of postnatal depression (OR = 1.61; 95% CI = 1.06, 2.43). All mothers of infants born in the study areas over a 1 year period were eligible to complete a questionnaire measuring maternal depression when the infant was 4 weeks of age. Thirty-three infants subsequently died from SIDS, and they were compared with 174 controls. Fifteen (45.5%) of the mothers of cases were depressed, compared with 28 (16.1%) of the mothers of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Four modifiable and other major risk factors for cot death: the New Zealand study

New Zealand's high mortality rate from sudden infant death syndrome (SIDS) prompted the development of the New Zealand Cot Death Study. A report of the analysis of the data from the first year has been published. This report now gives the major identified risk factors from the full 3 year data set. In this case-control study there were 485 infants who died from SIDS in the post-neonatal age group, and 1800 control infants, who were a representative sample of all hospital births in the study region. Obstetric records were examined and parental interviews were completed in 97.5% and 86.9% of subjects, respectively. As expected many risk factors for SIDS were confirmed including: lower socio-economic status, unmarried mother, young mother, younger school-leaving age of mother, younger age of mother at first pregnancy, late attendance at antenatal clinic, non-attendance at antenatal classes, Maori, greater number of previous pregnancies, the further south the domicile, winter, low birthweight, short gestation, male infant and admission to a special care baby unit. In addition, however, we identified four risk factors that are potentially amenable to modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Further evidence supporting a causal relationship between prone sleeping position and SIDS

A 3 year case-control study identifying the risk factors for SIDS was undertaken. Preliminary analysis of the data from the first year suggested that SIDS mortality could fall by 50% if the prevalence of the prone sleeping position changed from 40 to 0%. During the 3 year study the prevalence of the prone sleeping position among infants has fallen from 43% in the first year to 20% in the third year. SIDS mortality has fallen to 3.1/1000 live births, which is very close to that predicted. When considered with other available evidence this strongly supports a causal relationship between the prone sleeping position and SIDS.

Sudden infant death syndrome and weather temperature

The relationship between the days on which sudden infant death syndrome (SIDS) occurred and the daily minimum temperature was examined in Auckland (1979-1984) and Christchurch (1979-1987). There was a marked winter excess of deaths in both regions. There was a significant negative correlation between the monthly mean minimum temperature and SIDS rate for both regions (r = -0.43, n = 347, P less than 0.0001). The monthly mean minimum temperature describes SIDS mortality equally as well as the three variables of daily minimum temperature, season and geographical location. There was a significant association of SIDS with minimum temperature 4 and 5 days prior to the death after adjusting for the effect of monthly mean minimum temperature. The days preceding death were on average colder than the other days, but the effect was small, especially when compared with the magnitude of the temperature differences between consecutive months.

Mortality from coronary heart disease and incidence of acute myocardial infarction in Auckland, Newcastle and Perth

OBJECTIVE

To confirm the existence of regional differences in coronary death rates in Australia and New Zealand and to determine whether or not these are associated with parallel differences in the incidence of acute myocardial infarction.

DESIGN

Descriptive epidemiological study.

SETTING

Community based study.

SUBJECTS

Residents of Auckland, Newcastle and Perth aged 25-64 years admitted to hospital for acute myocardial infarction or dying from coronary heart disease between 1983 and 1987.

MAIN OUTCOME MEASURES

Definite acute myocardial infarction or coronary death classified according to the criteria of the World Health Organization MONICA project.

RESULTS

This study confirms the marked variation, evident from official statistics, in mortality rates from ischaemic heart disease between Newcastle (high), Auckland and Perth (low). A different pattern is observed for the incidence of acute myocardial infarction and there are also obvious differences between centres in the case fatality ratios for all acute coronary events combined. Newcastle has the highest rate for all coronary events, particularly in women. Auckland is characterised by substantially higher case fatality ratios compared with the two Australian cities. This is due especially to higher rates of coronary death outside hospital. Perth, which has the lowest mortality rates and case fatality ratios in both men and women, has rates for admission to hospital for acute myocardial infarction and all cases of ischaemic heart disease that are disproportionately high in relation to the corresponding mortality rates.

CONCLUSION

The differences in case fatality ratios between these three centres are not readily explained by artefacts related to enumeration or classification. Rather, they are most likely related to differences in the natural history of ischaemic heart disease in the three populations. Differences in medical management may also contribute to the substantial variation in mortality rates.

Results from the first year of the New Zealand cot death study

New Zealand's high mortality rate from the sudden infant death syndrome (SIDS) prompted the development of the New Zealand cot death study. This report of the preliminary analysis of the first year of the data gives the major identified risk factors. One hundred and sixty-two infants who died from SIDS were compared with 589 control infants, who were a representative sample of all hospital births in the study region. Obstetric records were examined and parental interviews were completed in 96% and 89% of subjects respectively. Data were available for all the variables in this study in 95% of those interviewed, thus 128 cases and 503 controls make up the subjects of this report. As expected we confirmed many risk factors for SIDS including: lower socioeconomic status, unmarried mother, young mother, younger school leaving age of mother, younger age of mother at first pregnancy, late attendance at antenatal clinic, nonattendant at antenatal classes, Maori, greater number of previous pregnancies, lower birth weight, shorter gestation, male infant, admission to neonatal intensive care unit. In addition, however, we identified three risk factors which are potentially amenable to modification. These were the prone sleeping position of baby (odds ratio = 3.53, 95% confidence interval 2.26, 5.54), maternal smoking (1-9 cigarettes/day OR = 1.87, 95% CI = 0.98, 3.54; 10-19/day OR = 2.64, 95% CI = 1.47, 4.74; 20+/day OR = 5.06, 95% CI = 2.86, 8.95) and breast feeding (OR = 2.93, 95% CI = 1.84, 4.67).(ABSTRACT TRUNCATED AT 250 WORDS)

A tool for measuring the asthma self-management competency of families

A tool for measuring a family's asthma self-management behaviour has been developed for a study examining the relationships of asthma self-management behaviour, knowledge, and psychosocial factors with various indices of morbidity in children with asthma. The tool involves a structured interview which includes three typical situations of asthma self-management (scenarios). Each of the scenarios is divided into graded challenges. A scoring schedule was developed according to the critical incidents of self-management inherent in each situation. This schedule was then applied to the verbatim transcripts of the subjects' responses. These were presented to 380 asthmatic children aged 5-11 yr and their primary caregivers. Inter-rater reliability, inter-rater agreement and test-retest reliability coefficients indicate that the scores obtained are stable across raters and time. Correlations between scores on different scenarios suggest there is a common factor of self-management competency across all scenarios, but families are better at some aspects of self-management than others. The distribution of scores for each scenario is presented. The place of this tool as a means of assessing self-management behaviour is discussed.

The interrelationship among bronchial hyperresponsiveness, the diagnosis of asthma, and asthma symptoms

Bronchial hyperresponsiveness (BHR) to inhaled histamine has often been cited as the gold standard in asthma diagnosis, but recently this has been questioned. This report assesses the relationship of BHR to asthma symptoms and asthma diagnosis in a large community-based sample of children. A total of 2,053 children 7 to 10 yr of age were randomly sampled from Auckland primary schools and assessed by a questionnaire and histamine inhalation challenge. In all, 14.3% had had asthma diagnosed, 29.6% reported having had one of the four respiratory symptoms in in the previous 12 months, and 15.9% had BHR (PD20 less than or equal to 7.8 mumol histamine). After a cumulative dose of 3.9 mumol histamine, the percent change in FEV1 from postsaline FEV1 was unimodally distributed, with those in whom asthma had been diagnosed dominating the severe end of the spectrum. However, 53% of those with BHR had no asthma diagnosis, and 41% had no current asthma symptoms. On the other hand, 48% of all subjects with diagnosed asthma and 42% of children with diagnosed asthma and current symptoms did not have BHR. Although severity of BHR tended to increase with wheezing frequency, all grades of severity (including no BHR) were found for any given frequency of wheeze. An existing diagnosis of asthma identified symptomatic children more accurately than did BHR, regardless of the criteria used for BHR or for "symptomatic" and irrespective of ethnic group. In conclusion, BHR is related to, but not identical to, clinical asthma. Bronchial challenge testing is an important tool of respiratory research, but cannot reliably or precisely separate asthmatics from nonasthmatics in the general community.

Hypoglycaemia in insulin dependent diabetic patients attending an outpatients' clinic

One hundred and fifty-eight patients with insulin dependent diabetes mellitus attending two Auckland outpatient clinics answered a questionnaire about hypoglycaemia. Almost all (98%) had experienced hypoglycaemic episodes and for 30% these were a major problem. Seventy-seven percent reported nocturnal hypoglycaemia, 39% of whom required external assistance during episodes. Forty-three percent had experienced coma, or convulsions during hypoglycaemia and a small group, 7%, had recurrent severe episodes. Twenty percent carried no diabetic identification and 13% did not routinely carry a glucose supply. Only 38% of patients kept glucagon at home. Forty percent of patients driving vehicles had experienced hypoglycaemia while driving and 13% reported traffic accidents attributed to hypoglycaemia. Hypoglycaemia is a major problem for many patients taking insulin. Improved education, wider availability of glucagon and more liberal glycaemic control of patients with problematic hypoglycaemia may be advisable.

Prevention of glucocorticoid-induced osteoporosis

There is increasing evidence that pamidronate and related compounds are effective in the prevention and treatment of osteoporosis. It is therefore of relevance to document the time course and mechanism of bisphosphonate action in this condition. To this end, the present study describes the biochemical responses to prophylactic treatment with oral pamidronate (APD, 150 mg/day) in 16 glucocorticoid-treated patients and contrasts them with those in 19 steroid-treated control subjects. Measurements were made over a period of 12 months. The treated patients showed a fall in urine hydroxyproline excretion at 6 weeks associated with a reduction in serum ionized calcium concentration, a rise in serum 1,25-(OH)2D3, and a nonsignificant rise in serum bone gla protein (BGP). In contrast to BGP, serum alkaline phosphatase activity declined at 6 weeks, falling further at 3 months. Between 3 and 12 months, BGP levels paralleled those of alkaline phosphatase and hydroxyproline, all these being significantly below their initial values, and the other parameters returned to baseline. There was a gradual increase in plasma phosphate concentrations in the treated group over the 12 month period. It is concluded that pamidronate produces an acute and sustained inhibition of bone resorption followed by a more gradual reduction in bone formation. This transient dissociation results in a reduction in serum calcium, leading to a rise in serum 1,25-(OH)2D3, which in turn stimulates BGP production. Thereafter, indices of bone turnover remain subnormal but serum calcium and 1,25-(OH)2D3 return to baseline.

Effects of carbamazepine on psychomotor performance in children as a function of drug concentration, seizure type, and time of medication

Fifty children with well-controlled seizures who were receiving carbamazepine (CBZ) monotherapy were tested on a battery of cognitive and motor tests. Time of CBZ was varied so that the children were tested both shortly after CBZ (when daily CBZ concentrations approached their peak) and before CBZ (when CBZ concentrations approached daily low or trough levels). Testing was blind so that the examiner was unaware of the time of CBZ or the child's type of seizure. Results showed only one group difference related to seizure type and no differences linked to overall CBZ concentration as measured in saliva. Peak and trough concentrations were associated with changes in several variables, however. The children performed significantly better shortly after CBZ (peak concentration day) on measures of seat activity, attention span, and motor steadiness, whereas response times appeared to be influenced in a task-specific manner.

Season of tumour detection influences factors predicting survival of patients with breast cancer

The rate of initial detection of breast tumours varies during the year in a seasonal fashion, more tumours being discovered in late spring/early summer than at other times of the year. This phenomenon is particularly pronounced in young women (less than 50 years) with progesterone receptor positive tumours. The present study investigates whether season of tumour detection influences the predictive capacity of several recognised prognostic and risk factors in patients with breast cancer. Axillary nodal status, tumour progesterone receptor status, and season of tumour detection significantly influenced survival in both older (greater than 50 yrs) and younger (less than 50 yrs) patients. Parity, lactational history, body mass index, tumour oestrogen receptor status, and patient age also influenced survival, but these effects were significant only in age groups less than 50 or greater than 50 yrs. Season of detection of tumour did not effect the prognostic significance of axillary nodal status. However, the effect of oestrogen receptor status on survival was more significant in patients who detected their tumours in the spring/summer compared with winter (odds ratio 0.52 and 0.73 respectively). Negative progesterone receptor status was associated with significant poorer survival only in patients with tumours found in the winter. There was a significant survival disadvantage for nulliparous compared with parous women with breast cancer who were greater than or equal to 50 years at diagnosis, and for women who had never lactated compared with those who had lactated, but this disadvantage was restricted to those who found their tumours in the summer. An increased body mass index (greater than or equal to 28) was associated with decreased survival, but this was significant only for those detecting tumours in winter. The increased incidence of detection of breast cancer in spring/summer may reflect cyclic influences on tumour growth. Such influences may be hormonal in nature and may underlie the effect of season of tumour detection on the prognostic influence of lactation, parity, body mass index, and oestrogen and progesterone receptor status in patients with breast cancer.

Season of initial discovery of tumour as an independent variable predicting survival in breast cancer

The month of initial detection of tumour was recorded in 2,245 patients with breast cancer and correlated with survival over a follow-up period of 1.5-10 years. Women who initially detected their breast cancer in spring/summer had a significantly longer survival than those detecting their tumour at other times of the year. Overall, this relationship was independent of nodal status, tumour size and hormone receptor status. However, when patients were divided into groups the survival advantage was significantly associated with receptor status and age. Women aged greater than or equal to 50 years with ER-positive and PR-positive tumours who discovered their initial tumour in spring/summer had significantly better survival than those detecting their tumours at other times of the year. Survival was also longer in women aged less than 50 years with receptor-negative tumours who initially found their tumours in spring/summer compared with the rest of the year. This study suggests that the season of first detection of a breast cancer relates significantly to the later behaviour of the tumour, and may reflect seasonal changes in hormone dependent growth.

Socioeconomic status in childhood asthma

This study examines the relationship between socioeconomic status (SES) and asthma prevalence and the use of asthma medication. One thousand and fifty European children aged eight and nine years were studied by parent completed questionnaire and histamine inhalation challenge. After controlling for sex of the child and for smokers in the house there were significantly higher lifetime (P = 0.029) and current (P = 0.046) prevalence rates of wheeze in children in low SES groups. There was no relationship between SES and asthma diagnosis, bronchial hyperresponsiveness (BHR: PD20 less than 7.8 mumol), or any combination of BHR with symptoms or diagnosis. The use of bronchodilators and asthma prophylactic drugs was less frequent in the low SES groups of children with wheeze in the last 12 months both with concurrent BHR or irrespective of BHR than in those in high SES groups.