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The article presents a study which explores the importance of identifying the accuracy of diagnostic tests in clinical studies. It states that diagnostic test accuracy studies evaluates the presence or absence of a disease which is expressed as test sensitivity and specificity. According to the authors, a clinically relevant disease must be used as a target condition for test accuracy studies. It is inferred that the definition of a disease as the target condition must be based on evidence from prognostic studies. INSET: Example of interpretation of test sensitivity and specificity....

Background: Privacy laws have recently created restrictions on how researchers can approach study participants. Method: In a randomised trial of 152 patients, 50-74 years old, in a family practice, 60 were randomly selected to opt-out and 92 to opt-in methods. Patients were sent an introductory letter by their doctor in two phases, opt-out before and opt-in after introduction of the new Privacy Legislation in December 2001. Opt-out patients were contacted by researchers. Opt-in patients were contacted if patients responded by email, free telephone number or a reply-paid card. Results: Opt-in recruited fewer patients (47%; 43/92) after invitation compared with opt-out (67%; 40/60); (-20%; [-4% to 36%]). No proportional difference in recruitment was found between opt-in and opt-out groups varied by age, sex or socioeconomic status. The opt-in group had significantly more people in active decision-making roles (+30%; [10% to 50%]; p=0.003). Non-significant trends were observed towards opt-in being Jess likely to include people with lower education (-11.8%; [-30% to 6.4%]; p=0.13) and people who were not screened (-19.1%; [-40.1% to 1.9%]; p=0.08). Opt-in was more likely to recruit people with a family history of colorectal cancer (+12.7%; [-2.8%, 28.2%]; p = 0.12). Conclusions: The number of participants required to be approached was markedly increased in opt-in recruitment. Existing participants (eg, screening attendees) with a vested interest such as increased risk, and those preferring an active role in health decision making and with less education were likely to be recruited in opt-in. Research costs and generalisability are affected by implementing privacy legislation. [ABSTRACT FROM AUTHOR]

The regression of lung function change on the initial lung function level is biased when the initial level is measured with random error. Several methods have been proposed to obtain unbiased estimates of regression coefficients in such circumstances. We apply these methods to examine the relationship between lung function loss over 11 years and its initial level in 433 men aged about 20 when first seen. On theoretical and practical grounds the best method is the correction of the regression coefficient using the reliability coefficient. This is defined as the ratio of the error free variance to the variance of the variable measured with error, and is easily estimated as the correlation between repeat measurements of the underlying level. In young men the loss of some lung functions (forced vital capacity [FVC], forced expiratory volume in one second [FEV1], forced expiratory flow in the middle half of expiration, and the ratio FEV1/FVC) do not appear to be related to initial level. [ABSTRACT FROM AUTHOR]

The effect is investigated of availability of free school milk on height gain in one year of six- and seven-year-old primary schoolchildren in England and Scotland, using data collected annually from 1972 to 1976. The height gain of children for whom milk was available for the whole year of observation was compared with that of children who had no milk. Out of 16 sex-country-year-specific analyses for children from manual social classes only, 13 showed no significant evidence of greater height gain in children who had milk. Comparison of children from Social Classes IV and V (semi-skilled and unskilled) showed no greater increase in height for those who had milk, nor was there a difference in height gain between manual social class children according to the number of glasses of milk they drank a day at home or at school. We concluded that, given the standard of living at the time of the survey, the drinking of free school milk did not increase the growth rate of six- and seven-year-old children. [ABSTRACT FROM AUTHOR]

Family factors associated with the incidence of asthma and wheezing during childhood have been studied in a cohort of over 2000 children who, together with their families, were followed-up for five years. Episodes of wheezing not regarded by the parents as asthma had a different pattern of association with family factors to that found for asthma. The outcome of the two conditions in terms of ventilatory function at the age of five years was also different, in that children with a history of asthma had a lower peak expiratory flow rate than did children with a history of non-asthmatic wheezing. [ABSTRACT FROM PUBLISHER]

In a study of a cohort of over 2000 children born between 1963 and 1965, the incidence of bronchitis and pneumonia during their first year of life was found to be associated with several family factors. The most important determinant of respiratory illness in these infants was an attack of bronchitis or pneumonia in a sibling. The age of these siblings, and their number, also contributed to this incidence. Parental respiratory symptoms, including persistent cough and phlegm, and asthma or wheezing, as well as parental smoking habits, had lesser but nevertheless important effects. Parental smoking, however, stands out from all other factors as the one most amenable to change in seeking to prevent bronchitis and pneumonia in infants. [ABSTRACT FROM PUBLISHER]

Study Question: What are the best red flags to indicate the possibility of fracture or malignancy in patients presenting with low back pain in primary, secondary, or tertiary care?, Summary Answer: Older age, prolonged corticosteroid use, severe trauma, and presence of a contusion or abrasion increase the likelihood of spinal fracture (likelihood was higher with multiple red flags); a history of malignancy increases the likelihood of spinal malignancy., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)