Table 3 Cox proportional hazard model for the association between the frequency of adding salt to food and incident sleep apnea among 488,196 participants in UK biobank: subgroup analyses

Age

 < 60

277,282

1 (ref)

1.02 (0.95, 1.1)

1.01 (0.91, 1.12)

1.17 (1.03, 1.33)

0.002

 ≥ 60

210,914

1 (ref)

1.24 (1.13, 1.35)

1.35 (1.21, 1.51)

1.33 (1.13, 1.57)

Sex

Females

268,295

1 (ref)

1.04 (0.94, 1.15)

1.14 (0.99, 1.3)

1.22 (1.03, 1.44)

0.47

Males

219,901

1 (ref)

1.15 (1.07, 1.23)

1.17 (1.07, 1.28)

1.24 (1.09, 1.41)

Race

White

460,225

1 (ref)

1.12 (1.06, 1.19)

1.17 (1.08, 1.26)

1.29 (1.16, 1.43)

0.01

Non-white

27,971

1 (ref)

0.95 (0.77, 1.16)

0.99 (0.76, 1.31)

0.9 (0.66, 1.23)

Townsend deprivation index

 < Median

243,789

1 (ref)

1.18 (1.07, 1.29)

1.29 (1.15, 1.45)

1.32 (1.1, 1.58)

0.003

 ≥ Median

243,803

1 (ref)

1.06 (0.99, 1.14)

1.07 (0.97, 1.18)

1.21 (1.07, 1.37)

Physical activity

Active

247,350

1 (ref)

1.14 (1.04, 1.25)

1.1 (0.98, 1.25)

1.29 (1.09, 1.52)

0.30

Insufficient

133,972

1 (ref)

1.07 (0.96, 1.19)

1.21 (1.05, 1.38)

1.17 (0.95, 1.44)

Inactive

75,333

1 (ref)

1.1 (0.97, 1.24)

1.13 (0.96, 1.31)

1.38 (1.15, 1.65)

Smoking status

Never

267,618

1 (ref)

1.11 (1.02, 1.21)

1.16 (1.02, 1.3)

1.2 (1.01, 1.42)

0.08

Ever

167,709

1 (ref)

1.08 (0.98, 1.18)

1.21 (1.08, 1.35)

1.36 (1.17, 1.59)

Current

51,036

1 (ref)

1.21 (1.03, 1.41)

1.04 (0.85, 1.26)

1.23 (0.98, 1.53)

Moderate drinking

Yes

256,789

1.05 (0.97, 1.14)

1.13 (1.02, 1.26)

1.25 (1.06, 1.46)

0.26

No

149,500

1 (ref)

1.14 (1.03, 1.26)

1.12 (0.98, 1.28)

1.19 (1.01, 1.4)

1 (ref)

BMI

 < 25

162,199

1 (ref)

1.25 (1.04, 1.51)

1.38 (1.07, 1.77)

1.28 (0.88, 1.84)

0.84

25.0–29.9

206,844

1 (ref)

1.09 (0.98, 1.21)

1.08 (0.94, 1.24)

1.13 (0.93, 1.38)

 ≥ 30.0

116,577

1 (ref)

1.1 (1.02, 1.18)

1.15 (1.04, 1.27)

1.28 (1.13, 1.45)

Hypertension

Yes

271,153

1 (ref)

1.12 (1.04, 1.19)

1.14 (1.04, 1.25)

1.16 (1.03, 1.31)

0.39

No

217,043

1 (ref)

1.08 (0.97, 1.21)

1.18 (1.02, 1.36)

1.43 (1.19, 1.71)

Diabetes

Yes

29,402

1 (ref)

1.17 (1.02, 1.34)

1.19 (0.99, 1.43)

1.04 (0.80, 1.36)

0.44

No

458,794

1 (ref)

1.1 (1.03, 1.17)

1.15 (1.06, 1.25)

1.28 (1.15, 1.43)

Atrial fibrillation

Yes

7107

1 (ref)

0.89 (0.66, 1.2)

1.17 (0.79, 1.71)

1.08 (0.63, 1.85)

0.50

No

481,089

1 (ref)

1.11 (1.05, 1.18)

1.14 (1.06, 1.23)

1.23 (1.11, 1.37)

Congestive heart failure

Yes

552

1 (ref)

0.3 (0.08, 1.14)

0.18 (0.02, 2)

1.56 (0.3, 8.03)

0.12

No

487,644

1 (ref)

1.11 (1.05, 1.18)

1.16 (1.08, 1.25)

1.24 (1.12, 1.37)

Stroke

Yes

8407

1 (ref)

1.14 (0.84, 1.56)

1.41 (0.97, 2.06)

1.45 (0.87, 2.4)

0.94

No

479,789

1 (ref)

1.11 (1.04, 1.17)

1.15 (1.06, 1.24)

1.24 (1.12, 1.37)

Asthma

Yes

58,893

1 (ref)

1.03 (0.9, 1.16)

1.04 (0.87, 1.23)

1.14 (0.92, 1.42)

0.08

No

429,303

1 (ref)

1.13 (1.06, 1.21)

1.18 (1.09, 1.29)

1.27 (1.13, 1.42)