Table 2 Adjusted incremental prevalence ratios (IPR) and confidence interval (CI) of 95%, and age-adjusted IPR stratified by different social groups, according to sex and periods. Basque Country, Spain. 1997–2013

 Age-adjusted

0.96

(0.79-1.16)

0.89

(0.76-1.04)

1.44

(1.23-1.69)

 Age+ws^a adjusted

1.00

(0.83-1.21)

0.90

(0.77-1.05)

1.32

(1.13-1.55)

 Age+ws+sc^b adjusted

1.00

(0.83-1.21)

0.90

(0.77-1.05)

1.34

(1.14-1.57)

 16-24

1.28

(0.74-2.23)

0.89

(0.56-1.42)

1.43

(0.86-2.39)

 25-34

1.02

(0.65-1.60

0.87

(0.61-1.25)

1.24

(0.82-1.87)

 35-44

0.79

(0.52-1.19)

0.91

(0.63-1.32)

1.73

(1.22-2.47)

 45-54

1.05

(0.73-1.53)

0.90

(0.68-1.21)

1.46

(1.09-1.94)

 55-64

0.78

(0.53-1.15)

0.93

(0.68-1.27)

1.23

(0.92-1.64)

Working status

 Employed

1.09

(0.86-1.39)

0.83

(0.69-1.01)

1.34

(1.10-1.64)

 Unemployed

0.74

(0.44-1.24)

0.95

(0.53-1.72)

1.45

(0.88-2.40)

 Student

0.84

(0.42-1.67)

0.97

(0.50-1.86)

1.76

(0.94-3.31)

 Retired, others

0.95

(0.60-1.51)

1.14

(0.79-1.63)

0.95

(0.66-1.36)

Social Class

 I

0.55

(0.29-1.04)

1.24

(0.70-2.21)

1.01

(0.60-1.71)

 II

1.22

(0.65-2.31)

1.05

(0.65-1.70)

1.10

(0.65-1.88)

 III

1.23

(0.82-1.84)

0.92

(0.69-1.23)

1.28

(0.93-1.77)

 IV

0.90

(0.68-1.19)

0.75

(0.59-0.97)

1.82

(1.43-2.32)

 V

0.92

(0.55-1.54)

1.00

(0.66-1.54)

1.38

(0.91-2.11)

 Age-adjusted

0.97

(0.85-1.12)

1.11

(0.99-1.24)

1.19

(1.07-1.34)

 Age+ws^a adjusted

1.00

(0.87-1.15)

1.13

(1.00-1.26)

1.18

(1.05-1.32)

 Age+ws+sc^b adjusted

1.01

(0.88-1.16)

1.12

(1.00-1.25)

1.17

(1.04-1.31)

 16-24

1.08

(0.75-1.55)

1.10

(0.80-1.51)

1.25

(0.88-1.77)

 25-34

1.10

(0.80-1.51)

1.03

(0.78-1.36)

1.29

(0.96-1.74)

 35-44

1.00

(0.74-1.35)

1.07

(0.82-1.40)

1.40

(1.08-1.81)

 45-54

0.81

(0.61-1.06)

1.26

(1.02-1.56)

0.99

(0.81-1.22)

 55-64

0.94

(0.71-1.25)

1.07

(0.87-1.32)

1.14

(0.94-1.38)

Working status

 Employed

1.04

(0.82-1.32)

1.07

(0.90-1.27)

1.12

(0.95-1.32)

 Unemployed

0.85

(0.54-1.35)

1.25

(0.77-2.02)

1.56

(1.05-2.31)

 Homemaker

0.94

(0.76-1.16)

1.25

(1.03-1.52)

1.15

(0.93-1.42)

 Student

1.16

(0.74-1.81)

0.93

(0.63-1.38)

1.44

(0.94-2.20)

 Retired,others

0.74

(0.42-1.30)

0.94

(0.63-1.41)

0.93

(0.64-1.35)

Social Class

 I

1.10

(0.64-1.92)

1.00

(0.65-1.55)

1.55

(1.04-2.33)

 II

0.93

(0.59-1.46)

1.07

(0.74-1.56)

1.00

(0.67-1.49)

 III

1.18

(0.88-1.58)

1.05

(0.85-1.30)

1.16

(0.92-1.46)

 IV

0.93

(0.76-1.15)

1.16

(0.96-1.39)

1.21

(1.01-1.45)

 V

0.83

(0.59-1.16)

1.08

(0.82-1.42)

1.13

(0.88-1.46)