First author

Year

Country

Source of cases

Source of controls

Number of cases

Number of controls

Study quality

Oka S

2014

Japan

Hospital-based

Population-based

1480

800

9

Prifti-Kurti M

2014

Albanian

Hospital-based

Population-based

100

191

7

Djidjik R

2014

Algeria

Hospital-based

Population-based

134

132

9

Shimane K

2013

Japan

Hospital-based

Population-based

2410

911

8

Nordang GB

2013

Norway

Hospital-based

Population-based

950

933

8

Balandraud N

2013

France

Hospital-based

Population-based

857

2187

8

Ucar F

2012

Turkey

Hospital-based

Population-based

291

253

6

Rheumatology Unit

2012

Sweden

Hospital-based

Population-based

1076

1612

9

Ben Hamad M

2012

Tunisia

Hospital-based

Population-based

142

123

8

Mackie SL

2012

Japan

Hospital-based

Population-based

3657

1357

9

Terao C

2011

Japan

Hospital-based

Population-based

869

2008

7

Ding B

2009

Sweden

Hospital-based

Population-based

1895

2389

9