Minimal error in self-report of having had DXA, but self-report of its results was poor.
OBJECTIVE
To examine the validity of both self-report of having had dual-energy x-ray absorptiometry (DXA) and self-reported DXA test results.


METHODS
Participants were recruited in 2003 and 2004 from a population-based study of women aged 65-90 years examining osteoporosis management in Ontario, Canada (N=871). Women reporting having had a DXA were eligible and asked to report the results of their most recent test. Participant responses were compared against DXA reports obtained from physicians.


RESULTS
We obtained 413 (81%) physician records among the 510 women who reported having had a DXA test. Of these, the positive predictive value for self-report of having had a DXA was 93%. The weighted kappa statistic for the agreement between self-report and actual DXA results was 0.42 (95% confidence interval=0.34-0.49). Although 84% of those with normal bone reported this, only 29% of those with osteopenia and 62% with osteoporosis reported their results correctly. Self-report of a clinical diagnosis of osteoporosis was better among those with a low trauma fracture, yet underestimated osteoporosis prevalence by 24%.


CONCLUSIONS
There is minimal measurement error in self-report of having had a DXA test. Self-report of DXA results will underestimate osteoporosis prevalence and is not a good proxy for clinical diagnosis.
Cadarette
Suzanne M
SM
Osteoporosis Research Program, Women's College Hospital, Toronto, Ontario, Canada. s.cadarette@utoronto.ca
Beaton
Dorcas E
DE
Gignac
Monique A M
MA
Jaglal
Susan B
SB
Dickson
Leigh
L
Hawker
Gillian A
GA
D015502:Absorptiometry, Photon / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000175:diagnosis / Q000523:psychology; D005260:Female; D006801:Humans; D015663:Osteoporosis, Postmenopausal / Q000175:diagnosis* / Q000523:psychology; D011237:Predictive Value of Tests; D012650:Self Disclosure; D012680:Sensitivity and Specificity