TABLE 2

Newcastle–Ottawa scale to evaluate the methodological quality of cohort studies included in the systematic review

	First author [ref.]
	Sack [24]	Sesé [14]	Winterbottom [15]	Singh [23]	Conti [17]	Johannson [13]	Johannson [16]
Representativeness of the exposed cohort (patients who developed ILD or had acute exacerbations of ILD)
Truly representative of community-based dwellers	•	•	•	•	•		•
Somewhat representative
Selected group of dwellers						•
No description of the derivation of the cohort
Selection of the non-exposed cohort (patients who did not develop ILD or had exacerbations of ILD)
Drawn from the same community as the exposed cohort^#	•	•	•	•	•	•	•
Drawn from a different source
No description of the origin of the non-exposed cohort
Ascertainment of exposure
Secure record^#	•	•	•	•	•	•	•
Structured interview^#
Written self-report
No description
Demonstration that the outcome of interest was not present at start of study
Yes^#	•	•	•	•	•	•	•
No
Comparability of cohorts on the basis of design or analysis
Study controls for lung diseases^#	•	•	•	•	•	•	•
Study controls for any additional factor^#	•	•	•	•	•	•	•
Assessment of outcome
Independent blind assessment^#			•			•
Record linkage^#	•	•		•	•		•
Self-report
No description
Was the follow-up long enough for outcomes to occur
Yes^#	•	•	•	•	•		•
No						•
Adequacy of follow-up of the cohorts
Complete follow-up: all subjects accounted for^#	•	•	•	•	•	•	•
Subjects lost to follow-up unlikely to introduce bias (small number lost) follow-up, or description provided of those lost^#
Low follow-up rate and no description of those lost
No statement

^#: study satisfies the question.