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Biomedical subjects

D Strachan

Publications and source records attributed to D Strachan.

At least 19 recordsLinked to original sources
PubMed2000

Epidemiology of pneumothorax in England.

BACKGROUND: Little is known of the epidemiology of pneumothorax. Routinely available data on pneumothorax in England are described. METHODS: Patients consulting in primary care with a diagnosis of pneumothorax in each year from 1991 to 1995 inclusive were identified from the General Practice Research Database (GPRD). Emergency hospital admissions for pneumothorax were identified for the years 1991-4 from the Hospital Episode Statistics (HES) data. Mortality data for England & Wales were obtained for 1950-97. Analyses of pneumothorax rates by age and sex were performed for all data sources. Seasonal and geographical analyses were carried out for the HES data. RESULTS: The overall person consulting rate for pneumothorax (primary and secondary combined) in the GPRD was 24. 0/100 000 each year for men and 9.8/100 000 each year for women. Hospital admissions for pneumothorax as a primary diagnosis occurred at an overall incidence of 16.7/100 000 per year and 5.8/100 000 per year for men and women, respectively. Mortality rates were 1. 26/million per year for men and 0.62/million per year for women. The age distribution in both men and women showed a biphasic distribution for both GP consultations and hospital admissions. Deaths showed a single peak with highest rates in the elderly. There was an urban-rural trend observed for hospital admissions in the older age group (55+ years) with admission rates in the conurbations significantly higher than in the rural areas. Analysis for trends in mortality data for 1950-97 showed a striking increase in the death rate for pneumothorax in those aged 55+ years between 1960 and 1990, with a steep decline in the 1990s. Mortality in the younger age group (15-34 years) remained low and constant. CONCLUSION: There is evidence of two epidemiologically distinct forms of spontaneous pneumothorax in England. The explanation for the rise and fall in mortality for secondary pneumothorax is obscure.

Adolescent↗
PubMed2000

The effectiveness of topical treatment in discharging ears with in-dwelling ventilation tubes.

The efficacy and tolerability of topical treatment (both drops and spray) in the treatment of otorrhoea in those ears with ventilation tubes in-situ was studied. Sixty patients were randomised into two treatment groups. One group used an antibacterial/anti-inflammatory ear drop preparation (Otosporin) and the other group a similar preparation administered as an ear spray (Otomize). A 'blind' clinical assessment was made one and three weeks after commencing treatment. Both treatments (drops and spray) significantly improved patients' symptoms and signs after one week (p < 0.001). The spray was significantly easier to administer (p < 0.01) and caused less discomfort on application (p < 0.02).

Administration, Topical↗
PubMed1999

Worldwide variations in the prevalence of symptoms of atopic eczema in the International Study of Asthma and Allergies in Childhood.

BACKGROUND: Little is known about the prevalence of atopic eczema outside Northern Europe. OBJECTIVES: We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world. METHODS: A cross-sectional questionnaire survey was conducted on random samples of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world. Those children with a positive response to being questioned about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema. Children whose atopic eczema symptoms resulted in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema. RESULTS: Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers. The prevalence range for symptoms of atopic eczema was from less than 2% in Iran to over 16% in Japan and Sweden in the 6 to 7 year age range and less than 1% in Albania to over 17% in Nigeria for the 13 to 14 year age range. Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe, and lower prevalences were reported in Eastern and Central Europe and Asia. Similar patterns were seen for symptoms of severe atopic eczema. CONCLUSIONS: Atopic eczema is a common health problem for children and adolescents throughout the world. Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups, suggesting that environmental factors may be critical in determining disease expression. Studies that include objective skin examinations are required to confirm these findings.

Adolescent↗
PubMed1999

The contribution of 'holiday deaths' to seasonal variations in asthma mortality in England and Wales.

BACKGROUND: In younger age groups there is a summer peak in asthma deaths, but whether this is due to social or environmental factors is not known. One suggested social factor is a summer holiday away from home during which there may be a lack of compliance with medication or greater difficulty in getting medical help. In older age groups there is a winter peak in asthma deaths. OBJECTIVE: To study the contribution of 'holiday deaths' to seasonal variations in asthma mortality in England and Wales. METHODS: Routinely collected mortality statistics were used (all asthma deaths of persons dying in England and Wales, 1991-93 and 1995). Deaths occurring 40 miles or more from home were estimated using the District Health Authority in which the person was usually resident; the registration district of death; and the 'transferability code' (derived by the Office for National Statistics). RESULTS: There were 484 asthma deaths in people aged 0-34 years, and 6337 asthma deaths in people aged 35 years or more. Deaths estimated to occur 40 miles or more from home contributed little (16%) to the summer peak in asthma deaths age 0-34 years, and nothing to the winter peak in asthma deaths age 35 years or more. CONCLUSIONS: Holidays away from home do not play an important part in explaining the seasonal variation of either young or old asthma deaths. Other social or environmental factors are more important.

Adolescent↗
PubMed1999

Use of the General Practice Research Database (GPRD) for respiratory epidemiology: a comparison with the 4th Morbidity Survey in General Practice (MSGP4).

BACKGROUND: The General Practice Research Database (GPRD) covers over 6% of the population of England and Wales and holds data on diagnoses and prescribing from 1987 onwards. Most previous studies using the GPRD have concentrated on drug use and safety. A study was undertaken to assess the validity of using the GPRD for epidemiological research into respiratory diseases. METHODS: Age-specific and sex-specific rates derived from the GPRD for 11 respiratory conditions were compared with patient consultation rates from the 4th Morbidity Survey in General Practice (MSGP4). Within the GPRD comparisons were made between patient diagnosis rates, patient prescription rates, and patient "prescription plus relevant diagnosis" rates for selected treatments. RESULTS: There was good agreement between consultation rates in the MSGP4 and diagnosis or "prescription plus diagnosis" from the GPRD in terms of pattern and magnitude, except for "acute bronchitis or bronchiolitis" where the best comparison was the combination category of "chest infection" and/or "acute bronchitis or bronchiolitis". Within the GPRD, patient prescription rates for inhalers, tuberculosis or hayfever therapy showed little similarity with diagnosis only rates but a similarity was seen with the combination of "prescription plus diagnosis" which may be a better reflection of morbidity than diagnosis alone. CONCLUSIONS: The GPRD appears to be valid for primary care epidemiological studies by comparison with MSGP4 and offers advantages in terms of large size, a longer time period covered, and ability to link prescriptions with diagnoses. However, careful interpretation is needed because not all consultations are recorded and the coding system used contains terms which do not directly map to ICD codes.

Adult↗
PubMed1998

First-aid treatment of epistaxis--confirmation of widespread ignorance.

A survey of 500 members of the public was carried out in which they were asked how they would deal with a nose bleed. Only 50 out of 443 responses were judged as being correct, confirming a clinical impression, long held by those dealing with epistaxis, that there is a high level of ignorance as to the correct first aid treatment. The survey also suggested that the lack of knowledge was not confined to the general public but evident in those trained in healthcare.

Epistaxis↗
PubMed1998

Acute asthma epidemics, weather and pollen in England, 1987-1994.

Recent epidemics of acute asthma have caused speculation that, if their causes were known, early warnings might be feasible. In particular, some epidemics seemed to be associated with thunderstorms. We wondered what risk factors predicting epidemics could be identified. Daily asthma admissions counts during 1987-1994, for two age groups (0-14 yrs and > or = 15 yrs), were measured using the Hospital Episodes System (HES). Epidemics were defined as combinations of date, age group and English Regional Health Authority (RHA) with exceptionally high asthma admission counts compared to the predictions of a log-linear autoregression model. They were compared with control days 1 week before and afterwards, regarding seven meteorological variables and 5 day average pollen counts for four species. Fifty six asthma epidemics were identified. The mean density of sferics (lightning flashes), temperature and rainfall on epidemic days were greater than those on control days. High sferics densities were overrepresented in epidemics. Simultaneously high sferics and grass pollen further increased the probability of an epidemic, but only to 15% (95% confidence interval 2-45%). Two thirds of epidemics were not preceded by thunderstorms. Thunderstorms and high grass pollen levels precede asthma epidemics more often than expected by chance. However, most epidemics are not associated with thunderstorms or unusual weather conditions, and most thunderstorms, even following high grass pollen levels, do not precede epidemics. An early warning system based on the indicators examined here would, therefore, detect few epidemics and generate an unacceptably high rate of false alarms.

Adolescent↗
PubMed1998

Statistical methods. Childhood asthma.

Statistical methods that are applied to trials of early or prophylactic interventions in childhood asthma may differ in important respects from those currently used for therapeutic trials in established asthma, which typically involve randomization of individuals and measurement of within-individual changes in continuous measures of disease severity. Randomization of small numbers of larger units (e.g., health centres) is less effective for controlling confounding than randomization of individuals. Because early interventions are by definition targeted at healthy children or those with mild disease, outcomes cannot usually be assessed as within-subject changes, but are analysed as between-subject comparisons of traits, states or events. Methods derived from observational epidemiology, including multiple regression, logistic regression and proportional hazards regression, are appropriate here. When there are repeated measures of outcome (such as lung function monitored at intervals through childhood), random effects models or mixed longitudinal models may be used. Calculations of sample size need to take into account the proposed form of randomization and analysis, and also the efficacy of the intervention and degree of compliance. Multiple end-points should be ranked for importance at the start of a trial and greater weight attached to significant results for primary outcomes.

Anti-Asthmatic Agents↗
PubMed1997

Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC).

BACKGROUND: As part of the International Study of Asthma and Allergies in Childhood (ISAAC), prevalence surveys were conducted among representative samples of school children from locations in Europe, Asia, Africa, Australia, North and South America. SUBJECTS: 257,800 children aged 6-7 years from 91 centres in 38 countries, and 463,801 children aged 13-14 years from 155 centres in 56 countries. METHODS: Written symptom questionnaires were translated from English into the local language for self-completion by the 13-14-year-olds and completion by the parents of the 6-7-year-olds. Rhinitis was described as a problem with sneezing, or a runny, or blocked nose when you (your child) DID NOT have a cold or the flu. Additional questions were asked about rhinitis associated with itchy-watery eyes, interference with activities and a history of hay fever ever. RESULTS: The prevalence of rhinitis with itchy-watery eyes ("rhinoconjunctivitis") in the past year varied across centres from 0.8% to 14.9% in the 6-7-year-olds and from 1.4% to 39.7% in the 13-14-year-olds. Within each age group, the global pattern was broadly consistent across each of the symptom categories. In centres of higher prevalence there was great variability in the proportion of rhinoconjunctivitis labelled as hay fever. The lowest prevalences of rhinoconjunctivitis were found in parts of eastern Europe, south and central Asia. High prevalences were reported from centres in several regions. CONCLUSION: These results suggest substantial worldwide variations in the prevalence and labelling of symptoms of allergic rhinoconjunctivitis which require further study. These differences, if real, may offer important clues to environmental influences on allergy.

Adolescent↗
PubMed1997

Effect of thunderstorms and airborne grass pollen on the incidence of acute asthma in England, 1990-94.

BACKGROUND: Thunderstorms and prior grass pollen counts were investigated as predictors of daily hospital admissions for asthma in England. This study was motivated by reports in the literature of spectacular asthma epidemics associated with thunderstorms, particularly in the grass pollen season. METHODS: Asthma admissions for two age groups (0-14 years and 15 and over) were measured using the Hospital Episodes System (HES) in the 14 regional health authorities (RHAs) in England. Thunderstorms were measured daily in each RHA using densities of sferics (lightning flashes). Relative asthma excesses for moderate positive and exceptionally high sferic densities, with or without previous high grass pollen counts, were measured using log linear autoregression--allowing for weekly, seasonal, and longer term background variation--and pooled over RHAs by calculating geometric means. RESULTS: Relative risks from all RHAs were pooled to form geometric means. Exceptional sferic densities were associated with a relative excess risk of around 25% in both age groups. Moderate sferic densities were associated with a smaller excess, statistically significant in the two age groups taken together. In five RHAs in which grass pollen counts were available, high pollen counts for the previous five days were associated with an amplification of the excess associated with thunderstorms. CONCLUSION: Very large sferic densities are associated with moderate rises in hospital admissions for acute asthma. However, typical thunderstorm days are not associated with spectacular asthma epidemics of the scale previously reported in the literature. Thunderstorm-associated excesses are amplified after a run of high pollen counts.

Acute Disease↗
PubMed1997

Thunderstorm-related asthma--the epidemic of 24/25 June 1994.

BACKGROUND: A large epidemic of asthma occurred following a thunderstorm in southern and central England on 24/25 June 1994. A collaborative study group was formed. OBJECTIVES: To describe the epidemic and the meteorological, aerobiological and other environmental characteristics associated with it. METHODS: Collation of data from the Meteorological Office, the Pollen Research Unit, the Department of the Environment's Automatic Urban Network, from health surveillance by the Department of Health and the National Poisons Unit, from clinical experience in general practice and hospitals, and from an immunological study of some of the affected cases from north east London. RESULTS: The thunderstorm was a Mesoscale Convective System, an unusual and large form of storm with several centres and severe wind gusts. It occurred shortly after the peak grass pollen concentration in the London area. A sudden and extensive epidemic occurred within about an hour affecting possibly several thousand patients. Emergency services were stretched but the epidemic did not last long. Cases had high serum levels of IgE antibody to mixed grass pollen. CONCLUSION: This study supports the view that patients with specific IgE to grass pollen are at risk of thunderstorm-related asthma. The details of the causal pathway from storm to asthma attack are not clear. Case-control and time series studies are being carried out.

Adult↗
PubMed1996

Physician prescribing practices: What do we know? Where do we go? How do we get there?

Although drug prescribing is one of the most important components of medical care, little is known about how prescribing practices are determined and how they can be influenced. Enhancing the quality and effectiveness of drug prescribing requires research and better dissemination of information to physicians and other decision-makers. This requires a collaborative effort and a coordinated action plan. Participants at the Physician Prescribing Practices Workshop, held in Ottawa in October 1995, addressed issues and made recommendations in three areas: current knowledge and issues for research in the field of prescribing practices, and the capacity of Canadian databases to study these issues, strategies for disseminating and implementing knowledge and research findings to enhance the quality of prescribing; and the formation of a network to foster collaboration among stakeholders.

Canada↗
PubMed1996

C reactive protein and its relation to cardiovascular risk factors: a population based cross sectional study.

OBJECTIVE: To test the hypothesis that minor chronic insults such as smoking, chronic bronchitis, and two persistent bacterial infections may be associated with increases in C reactive protein concentration within the normal range and that variations in the C reactive protein concentration in turn may be associated with levels of cardiovascular risk factors and chronic coronary heart disease. DESIGN: Population based cross sectional study. SETTING: General practices in Merton, Sutton, and Wandsworth. SUBJECTS: A random sample of 388 men aged 50-69 years from general practice registers. 612 men were invited to attend and 413 attended, of whom 25 non-white men were excluded. The first 303 of the remaining 388 men had full risk factor profiles determined. INTERVENTIONS: Measurements of serum C reactive protein concentrations by in house enzyme linked immunosorbent assay (ELISA); other determinations by standard methods. Coronary heart disease was sought by the Rose angina questionnaire and Minnesota coded electrocardiograms. MAIN OUTCOME MEASURES: Serum C reactive protein concentrations, cardiovascular risk factor levels, and the presence of coronary heart disease. RESULTS: Increasing age, smoking, symptoms of chronic bronchitis, Helicobacter pylori and Chlamydia pneumoniae infections, and body mass index were all associated with raised concentrations of C reactive protein. C Reactive protein concentration was associated with raised serum fibrinogen, sialic acid, total cholesterol, triglyceride, glucose, and apolipoprotein B values. C Reactive protein concentration was negatively associated with high density lipoprotein cholesterol concentration. There was a weaker positive relation with low density lipoprotein cholesterol concentration and no relation with apolipoprotein A I value. C Reactive protein concentration was also strongly associated with coronary heart disease. CONCLUSION: The body's response to inflammation may play an important part in influencing the progression of atherosclerosis. The association of C reactive protein concentration with coronary heart disease needs testing in prospective studies.

Aged↗
PubMed1996

Socioeconomic factors and the development of allergy.

Allergy has been associated with relative affluence for over a century, and more recently a substantially lower prevalence of sensitisation to common aeroallergens has been demonstrated in parts of Eastern Europe compared with Western and Northern Europe. One of the strongest risk factors for atopy is small sibship size. This applies in both affluent and less affluent families, and in both Western and Eastern Europe. The protective effect of older siblings is stronger than that of younger siblings, suggesting that family structure in early life is important. A unifying explanation for all these observations would be that allergic sensitisation can be prevented by infections acquired during early childhood. Direct evidence in support of this hypothesis is still awaited, but immunological mechanisms have been suggested. A reduction in infection offers a more coherent explanation of past and current trends in allergy prevalence than does an increase in exposure to environmental chemicals.

Air Pollution↗
PubMed1996

Sudden sensorineural deafness and hormone replacement therapy.

Whilst the oral contraceptive pill (OC) has been implicated on a number of occasions as a cause of sensorineural hearing loss, there are no published reports linking hormone replacement therapy (HRT) to otological symptoms. A case of sensorineural loss with tinnitus following commencement of HRT is described, followed by a discussion outlining the fundamental differences between the OC and HRT, thus explaining why a vascular aetiology is unlikely. It is hypothesized that otological symptoms in such cases may be due to the effect of oestrogens on electrolyte balance disturbing inner ear function and also a direct effect on the auditory pathways mediated in part by alterations in neurotransmitter receptor concentrations.

Audiometry, Pure-Tone↗
PubMed1996

Enzyme linked immunosorbent assay for detecting benzodiazepines in urine.

A relatively simple ELISA technique was developed for the detection of a range of benzodiazepines (BZs) in urine. The assay employs a mouse anti-oxazepam antibody that is highly specific for the BZs. The limit of detection using 10 microliters samples of urine was 0.3 microgram ml-1 oxazepam. N-Desmethyldiazepam showed equal cross-reactivity to oxazepam, 11 BZs cross-reacted weakly and flurazepam and chlordiazepoxide did not cross-react at levels reported to be found in urine. No cross-reactivity was observed with drugs of abuse and a range of therapeutic drugs commonly found in urine. The assay was used as a screen to detect the presence of BZs in urine from 88 addicts that had been screened by the EMIT technique and a radioreceptor assay (RRA) for BZs. The ELISA produced two false negatives that were EMIT and RRA positive whereas the EMIT produced four different false negatives that were positive by both ELISA and RRA. Thirty-three positives were common to all three assays. The ELISA was also used to monitor nitrazepam-like activity in the urine of a greyhound receiving 5 mg oral medication and the results were compared with those obtained by RRA. Both assays were able to detect nitrazepam-like activity for up to 10 h post-administration.

Animals↗