Table 3 Hazard ratios (95% confidence intervals) for incident hypertension in men grouped by household income

From: Household income and the risk of incident hypertension in employees at multiple workplaces in Japan: J-HOPE

 

Household income (million Japanese yen/year) [(thousand US dollars/year)]

 

<5.0 [<60.8]

5.0–7.9 [60.8–97.2]

8.0–9.9 [97.3–121.6]

≥10.0 [≥121.7]

P value for trend

Overall

     

 Participants

667

1412

587

487

 

 Person-years of follow-up

1217

2564

1044

839

 

 Cases of incident hypertension

45

188

89

105

 

 Incidence rate (/1000 person-years)

37.0

73.3

85.2

125.1

 

 Hazard ratio, model 1

1.00 (reference)

1.41 (1.02–2.00)

1.35 (0.92–1.98)

1.62 (1.10–2.39)

0.048

 Hazard ratio, model 2

1.00 (reference)

1.52 (1.08–2.18)

1.49 (0.98–2.27)

1.92 (1.23–3.01)

0.016

 Hazard ratio, model 3

1.00 (reference)

1.49 (1.06–2.13)

1.46 (0.96–2.22)

1.85 (1.18–2.90)

0.024

 Hazard ratio, model 4

1.00 (reference)

1.48 (1.06–2.12)

1.48 (0.97–2.24)

1.85 (1.19–2.90)

0.021

 Hazard ratio, model 5

1.00 (reference)

1.45 (1.03–2.07)

1.44 (0.95–2.19)

1.79 (1.15–2.81)

0.029

18–34 years old

     

 Participants

437

261

42

45

 

 Person-years of follow-up

808

463

70

80

 

 Cases of incident hypertension

21

27

5

6

 

 Incidence rate (/1000 person-years)

26.0

58.3

71.4

75.0

 

 Hazard ratio, model 1

1.00 (reference)

1.45 (0.71–2.98)

1.57 (0.47–4.45)

1.29 (0.43–3.33)

0.768

 Hazard ratio, model 2

1.00 (reference)

1.47 (0.70–3.15)

1.81 (0.50–5.86)

1.25 (0.36–3.88)

0.716

 Hazard ratio, model 3

1.00 (reference)

1.45 (0.69–3.09)

1.87 (0.51–6.10)

1.31 (0.38–4.10)

0.726

 Hazard ratio, model 4

1.00 (reference)

1.44 (0.68–3.11)

1.97 (0.53–6.45)

1.20 (0.35–3.77)

0.681

 Hazard ratio, model 5

1.00 (reference)

1.43 (0.67–3.07)

2.18 (0.59–7.28)

1.26 (0.36–3.98)

0.628

35–49 years old

     

 Participants

175

972

397

278

 

 Person-years of follow-up

327

1787

726

474

 

 Cases of incident hypertension

13

123

52

62

 

 Incidence rate (/1000 person-years)

39.8

68.8

71.6

130.8

 

 Hazard ratio, model 1

1.00 (reference)

1.49 (0.86–2.80)

1.37 (0.74–2.69)

2.01 (1.08–3.99)

0.094

 Hazard ratio, model 2

1.00 (reference)

1.69 (0.96–3.22)

1.57 (0.81–3.22)

2.49 (1.23–5.30)

0.039

 Hazard ratio, model 3

1.00 (reference)

1.60 (0.91–3.06)

1.51 (0.78–3.11)

2.34 (1.16–4.99)

0.064

 Hazard ratio, model 4

1.00 (reference)

1.75 (0.99–3.33)

1.63 (0.84–3.34)

2.53 (1.25–5.40)

0.042

 Hazard ratio, model 5

1.00 (reference)

1.64 (0.93–3.14)

1.55 (0.80–3.19)

2.36 (1.16–5.04)

0.070

50–69 years old

     

 Participants

55

179

148

164

 

 Person-years of follow-up

82

314

248

285

 

 Cases of incident hypertension

11

38

32

37

 

 Incidence rate (/1000 person-years)

134.1

121.0

129.0

129.8

 

 Hazard ratio, model 1

1.00 (reference)

0.89 (0.43–1.97)

0.90 (0.41–2.07)

0.84 (0.39–1.92)

0.977

 Hazard ratio, model 2

1.00 (reference)

0.84 (0.39–1.91)

0.95 (0.42–2.28)

1.01 (0.42–2.55)

0.915

 Hazard ratio, model 3

1.00 (reference)

0.86 (0.40–1.94)

0.99 (0.44–2.39)

1.02 (0.42–2.61)

0.917

 Hazard ratio, model 4

1.00 (reference)

0.82 (0.38–1.85)

0.93 (0.41–2.20)

0.95 (0.40–2.39)

0.917

 Hazard ratio, model 5

1.00 (reference)

0.84 (0.39–1.91)

0.99 (0.44–2.37)

0.99 (0.41–2.52)

0.911

  1. Five different Cox proportional hazard regression models were used as follows:
  2. Model 1, adjusted for age, baseline systolic blood pressure, and worksite
  3. Model 2, adjusted for covariates included in model 1 + number of family members, smoking habit, and type of occupation
  4. Model 3, adjusted for covariates included in model 2 + alcohol drinking habit
  5. Model 4, adjusted for covariates included in model 2 + body mass index
  6. Model 5, adjusted for covariates included in model 2 + alcohol drinking habit and body mass index
  7. Hypertension was defined as systolic blood pressure ≥140 mmHg, diastolic blood pressure ≥90 mmHg, and/or self-reported hypertension [17]
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