Table 2.

Frequency of Accelerated or Rapid KOA Using Previously Reported Definitions Among Adults without Radiographic KOA at OAI Baseline

Term	Radiographic Change	Time Frame	Incidence in OAI
Accelerated OA [1, 3, 4]	KL 0 or 1 to KL 3 or 4	4 or 5 years	7.2%
Rapid Radiographic Change [47]	KL 0 or 1 then KL change > 2	4 or 5 years	12.4%
Fast JSW Loss [48]	> 0.25 mm medial JSW change	1 year	15.5 to 22.1%
Rapid Progressors [49]	> 1.05 mm medial JSW change	1 year	0.4 to 0.8%
Rapid Destructive Arthrosis [50]	> 2 mm JSW change or 50% narrowing	1 year	0%
Rapid Progressive OA Type 1 [46, 47]	> 2.00 mm JSW change	1 year	0%
Rapid Progressive OA Type 2 [46, 47]	abnormal bone loss or destruction	short period of time	0%

Note: KOA  knee osteoarthritis, OAI  Osteoarthritis Initiative, OA  osteoarthritis, JSW  joint space width