Table 2

Main results for the 87 identified potential cases of osteonecrosis

Definition using administrative data

Number of records meeting definition (percentage)

PPV for confirmed ON (prevalent and incident)

PPV for incident ON

Number of records needing review for every 1,000 with any ON code

Number of incident ON cases expected after review

At least 1 ON code

87 (100%)

90%

17%

1,000

170

More than 1 ON code

85 (98%)

92%

18%

980

176

At least 1 inpatient ON code

47 (54%)

100%

23%

540

124

(At least 1 ON code) and (no prior codes for OA)

25 (29%)

76%

24%

290

70

(At least 1 inpatient ON code) and (no prior codes for OA)

13 (15%)

100%

46%

150

69

OA, osteoarthritis; ON, osteonecrosis; PPV, positive predictive value.

Vlad et al. Arthritis Research & Therapy 2009 11:R89   doi:10.1186/ar2731