Table 1 Reasons for rejection of publications identified

IMMEDIATE REJECTS

Title of publication indicates it is irrelevant (abstract/paper unavailable)

Publication could not be obtained

PUBLICATION DOES NOT PROVIDE ORIGINAL DATA

Results the same as or superseded by another publication

Review (including guideline, handout, lecture, bibliography, meta-analysis)

Editorial

Comment, letter, interview or news article

Publication is a theoretical modelling exercise

STUDY POPULATION INAPPOPRIATE

Study of children or adolescents

Animal study

Study in population at high risk of respiratory disease, such as risky occupations

Study of alpha-1antitrypsin deficient subjects

Study of subjects with other coexisting diseases or conditions

Study of atypical populations

Subjects selected on smoking habits

Study of symptom-free or symptom-restricted populations

STUDY DESIGN INAPPROPRIATE

Not a case-control, prospective or cross-sectional study

Study of cases only

Control group not appropriate

Selection of subjects not clear

OUTCOME INAPPROPRIATE

Outcome not relevant

Study of undiagnosed disease

Study of disease exacerbation

USEFUL RESULTS BY SMOKING UNAVAILABLE

Never smokers not considered

No relevant results by smoking

Comparisons with never smokers and ex-smokers combined

Study of smokers of unusual cigarettes (e.g. chuttas)

Relative risks not calculable

Relative risks adjusted for symptoms or precursors of disease

Total rejected