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Table 2 Characteristics of studies and evaluation of Newcastle-Ottawa Scale

From: Causal assessment of smoking and tooth loss: A systematic review of observational studies

       

NOS

Study design

First author, year

Participants

Age range (years)

Definition of tooth loss

Focal point

Dose-response

Coding

Score

Cross-sectional study

Randolph, 2001

3,050 Mexican American

65-99

15+

F

NA

011 11 1

5*

 

Klein, 2004

2,764 American

53-96

1+

F

NA

011 11 1

5*

 

Tanaka, 2005

1,002 Japanese pregnant women

29.8 on average

1+

S

NA

010 11 0

3

 

Hanioka, 2007

2,200 Japanese

60-94

Total tooth loss

S

NA

101 10 1

4

 

Musacchio, 2007

1,226 Italian males

65+

Total tooth loss

S

NA

101 11 1

5*

 

Ojima, 2007

1,314 Japanese

20-39

1+

S

3/4 levels

111 01 1

5*

 

Hanioka, 2007

3,999 Japanese

40-94

9+

S

3/4 levels

111 11 1

6*

 

Mundt, 2007

2,501 German

25-59

15th percentile

F

3 levels

111 11 1

6*

 

Yanagisawa, 2009

547 Japanese males

55-75

9+

S

3 levels

110 11 0

4

 

Yanagisawa, 2010

1,088 Japanese males

40-75

9+

S

3 levels

110 11 0

4

       

NOS

Study design

First author, year

Participants

Age range (years)

Duration of observation

Focal point

Dose-response

Coding

Score

Cohort study

Slade, 1997

693 Australian

60+

2 years

F

NA

10 01 110

4

 

Krall, 2006

789 American males

21-84

36 years

S

NA

00 11 111

5*

 

Okamoto, 2006

740 Japanese males

30-59

4 years

S

3 levels

00 10 110

3

 

Dietrich, 2007

43,112 American male health professionals

40-75

16 years

S

5 levels

01 11 111

6*

 

Cunha-Cruz, 2008

12,264 American HMO members

45-61

3 years

A

NA

00 10 110

3

  1. Studies were conducted in Japan, the United States, Australia, Germany and Italy. A dose-response relationship was examined in 7 studies, and 8 studies (6 for cross-sectional and 2 for prospective cohort studies) were classified as high quality.
  2. S, smoking; F, factors including smoking; A, systemic antibodies; *evaluated for high-quality methodology by the modified Newcastle-Ottawa Scale (NOS). One star each was given for six and seven items for cross-sectional and cohort studies, respectively, if the methodology of a study satisfied the criterion. The items were divided according to three categories of selection, comparability and exposure for cross-sectional studies and selection, comparability and outcome for cohort studies. When a study satisfied all criteria, the star column appears as 111 11 1 for cross-sectional and 11 11 111 for cohort studies. Studies with total scores of five or more, three or four, and two or less were evaluated as high-, moderate- and low-quality studies, respectively.