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Table 3 Bone mineral density and prevalence of osteoporosis evaluated at the distal radius in three cohorts of women measured in 1970-74, 1987-93 and 1998-99.

From: Prevalence of osteoporosis and incidence of hip fracture in women - secular trends over 30 years

Measurementsa

Cohort

1970-74

Cohort

1987-93

Cohort

1998-99

P-

value

 

n = 106

n = 175

n = 178

 

Bone mineral density (mg/cm2)b

    

   Non-adjusted

438 (422, 454)

453 (439, 468)

461 (446, 477)

0.15d

   Age-adjusted

444 (430, 458)

460 (449, 471)

451 (440, 461)

0.17e

Prevalence of osteoporosis c

    

   Non-adjusted

15.1 (8.2, 22.0)

15.1 (9.7, 20.5)

14.9 (9.5, 20.2)

1.00f

   Age-adjusted

13.6 (6.1, 21.2)

14.7 (8.9, 20.5)

11.0 (8.4, 13.6)

1.00 g

  1. a The bone mineral density in the forearm was measured at a site 6 cm (distal radius) proximal to the styloid process of the ulna by single-photon absorptiometry.
  2. b Values are mean (95 percent confidence interval).
  3. c Values are percentages of valid measurements (95 percent confidence interval). Osteoporosis denotes a bone mineral density 2.5 SD below the bone mineral density in young healthy women.
  4. d Comparing all three cohorts by analysis of variance.
  5. e Comparing all three cohorts by analysis of covariance with adjustment for age.
  6. f Comparing all three cohorts by chi-squared test.
  7. g Comparing all three cohorts, with direct standardisation for age, by logistic regression.