Table 2

Methodological characteristics of studies.

Author (year)

Study design

Exposure assessment

Outcome assessment

Number of confounders controlled

Study quality score


Definition of smoking

Definition of non smoking

Method of assessingsmoking status

Definition ofpneumonia

Blinding ofassessors toexposure status (cohort studies)


Bacterial pneumonia


[12]

Case control

>1 cig/day

Never smoked

Medical history

2

0

3

7

[21]

Cohort

NR

Former and never, otherwise undefined

Questionnaire or clinical notes

1

0

4

5

[13]

Nested case-control

NR

NR

NR

2

1

0

3

[23]

Cohort

NR

NR

Interview

2

1

4

7

[14]

Cohort

NR

Never smokers <100 cigarettes in lifetime

NR

2

0

4

6

[15]

Cohort

NR

Not current smokers

NR

2

0

7

9

[16]

Cohort

NR

NR

Questionnaire

2

0

4

6

[17]

Cohort

NR

NR

Questionnaire

2

0

0

2

[18]

Case control

>6 cigs/day

NR

NR

2

0

0

3


Bacterial pneumonia and Pneumocystis jiroveci pneumonia


[19]

Cohort

NR

Self-defined

Clinical notes

0

0

4

4

[20]

Cohort

Cigarettes/day in multiple categories

NR

Questionnaire

1

0

0

2

[25]

Case control

NR

NR

Questionnaire

2

0

3

5


Pneumocystis jiroveci pneumonia only


[22]

Cohort

Defined according to daily cigarette consumption and change in smoking status over time

Not currently smoking

Questionnaire

2

0

2

6

[24]

Case control

Current tobacco use

Current non-smoking

Questionnaire and clinical notes

2

0

1

4


NR: not reported.

De et al. BMC Medicine 2013 11:15   doi:10.1186/1741-7015-11-15

Open Data