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Table 3 Rates of mortality from diseases of the respiratory system in winter and non-winter months, ratio of rates and relative change in winter:non-winter ratios for potential modifying factors; 1996–2000

From: Trends and determinants of excess winter mortality in New Zealand: 1980 to 2000

p-value

 

Rate per 10,000 person years (No of deaths)*

Winter:non-winter ratio (95% CI)‡ Unadjusted

Winter:non-winter ratio relative to baseline category§ (95% CI)‡

  

Winter

Non-winter

  

All

9.4 (5762)

5.5 (6178)

   

Age (years):

     

   0–4

0.9 (42)

0.4 (35)

2.40 (1.31, 4.41)

1.00

 

   5–14

0.0 (3)

0.0 (4)

1.50 (0.34, 6.58)

0.61 (0.13, 2.96)

 

   15–29

0.1 (16)

0.1 (26)

1.24 (0.62, 2.45)

0.50 (0.22, 1.11)

 

   30–59

1.1 (260)

0.7 (348)

1.49 (1.01, 2.18)

0.61 (0.35, 1.06)

 

   60–79

29.8 (2381)

17.5 (2796)

1.61 (1.31, 1.97)

0.67 (0.40, 1.11)

 

   80+

180.2 (3060)

103.6 (3509)

1.66 (1.40, 1.97)

0.67 (0.40, 1.13)

p = .56

Gender:

     

   Male

9.4 (2930)

5.9 (3501)

1.64 (1.40, 1.92)

1.00

 

   Female

9.4 (2932)

5.2 (3217)

1.74 (1.49, 2.03)

1.15 (0.99, 1.34)

p = .08

Ethnicity†:

     

   Non-Maori

9.0 (5328)

5.2 (6159)

1.68 (1.39, 2.02)

1.00

 

   Maori

15.7 (434)

9.9 (559)

1.58 (1.08, 2.33)

0.90 (0.72, 1.12)

p = .35

NZDep96:

     

   1–3

7.5 (1233)

4.6 (1504)

1.49 (1.10, 2.03)

1.00

 

   4–6

9.0 (1662)

5.3 (1948)

1.64 (1.23, 2.20)

1.13 (0.93, 1.37)

 

   7–10

10.9 (2867)

6.2 (3266)

1.80 (1.38, 2.35)

1.12 (0.93, 1.36)

p = .40

RHA:

     

   North

8.5 (1790)

4.8 (2012)

1.91 (1.37, 2.64)

1.00

 

   Midland

9.6 (1165)

5.6 (1369)

1.52 (1.08, 2.14)

0.87 (0.70, 1.08)

 

   Central

9.5 (1416)

5.8 (1728)

1.49 (1.06, 2.10)

0.95 (0.77, 1.17)

 

   South

10.6 (1391)

6.2 (1609)

1.71 (1.21, 2.42)

0.95 (0.77, 1.17)

p = .67

  1. * No of deaths in winter correspond to a 4 month period; non-winter, an 8 month period
  2. ‡ Generalised negative binomial regression model; overdispersion a linear combination of age group and ethnicity
  3. § Adjusted for all other covariates including covariate by winter interaction terms
  4. † Mortality rates have been age-standardised to account for different population structures of Maori and Non-Maori