Table 4.

Factors predicting radiological progression

Prognostic factor	Studies	Associations	Best-evidence synthesis
Patient variables
No association
Family history of OA			Moderate evidence for no association
	3 cohorts [25, 60, 65]	No, no, no
Body mass index			Moderate evidence for no association
	4 cohorts [25, 50, 61, 65]	No, no, no, no
Conflicting evidence
Higher age at baseline or at first symptoms			Conflicting evidence
	1 low risk of bias cohort [32] 4 cohorts [35, 50, 60, 65]	Positive No, positive, positive, no
Female			Conflicting evidence
	1 low risk of bias cohort [32] 6 cohorts [25, 27, 35, 50, 60, 65]	Positive No, no, no, no, positive, no
Disease characteristics
Faster or more progression
More limitations in physical function at baseline			Moderate evidence for more progression
	1 low risk of bias cohort [32] 1 cohort [60]	Positive Positive
Hip pain present at baseline or on most days for a least 1 month in the past year			Moderate evidence for more progression
	1 low risk of bias cohort [47] 1 cohort [60]	Positive Positive
No association
Forestier’s disease			Moderate evidence for no association
	3 cohorts [25, 50, 65]	No, no, no
Diabetes mellitus			Limited evidence for no association
	2 cohorts [25, 60]	No, no
Bilateral hip OA			Limited evidence for no association
	2 cohorts [25, 65]	No, no
Generalized OA			Limited evidence for no association
	2 cohorts [25, 65]	No, no
Chemical or imaging markers
Faster or more progression
Subchondral sclerosis			Moderate evidence for more progression
	1 low risk of bias cohort [47] 1 cohort [33]	Positive Positive
Neck width of the femoral head			Limited evidence for more progression
	1 low risk of bias cohort [21]	Positive
Osteocalcin (OC)			Limited evidence for less progression
	1 low risk of bias cohort [63]	Negative
No association
C-terminal telopeptide of collagen type I (CTX-I)			Strong evidence for no association
	2 low risk of bias cohorts [53, 63]	No, no
Cartilage oligomeric matrix protein (COMP)			Strong evidence for no association
	3 low risk of bias cohorts [44, 53, 63] 1 cohort [26]	No, no, no Positive
N-terminal telopeptide of collagen type I (NTX-I)			Strong evidence for no association
	2 low risk of bias cohorts [44, 63]	No, no
N-terminal propeptide of procollagen type I (PINP)			Strong evidence for no association
	2 low risk of bias cohorts [53, 63]	No, no
N-terminal propeptide of procollagen type III (PIIINP)			Strong evidence for no association
	2 low risk of bias cohorts [53, 63]	No, no
High-sensitive C-reactive protein (hs-CRP)			Moderate evidence for no association
	1 low risk of bias cohort [53] 1 cohort [45]	No No
Angle of the femoral head			Moderate evidence for no association
	1 low risk of bias cohort [21] 2 cohorts [20, 65]	No No, no
Acetabular osteophytes only			Moderate evidence for no association
	1 low risk of bias cohort [47] 1 cohort [33]	No No
N-terminal propeptide of procollagen type IIA (PIIANP)			Limited evidence for no association
	1 low risk of bias cohort [63]	No
Chondroitin sulphate 846 (CS846)			Limited evidence for no association
	1 low risk of bias cohort [63]	No
Cartilage glycoprotein 40 (YKL-40)			Limited evidence for no association
	1 low risk of bias cohort [53]	No
Matrix metalloproteinases (MMP-1)			Limited evidence for no association
	1 low risk of bias cohort [53]	No
Matrix metalloproteinases (MMP-3)			Limited evidence for no association
	1 low risk of bias cohort [53]	No
Neck length of the femoral head			Limited evidence for no association
	1 low risk of bias cohort [21]	No
Conflicting evidence
Bone mineral content			Conflicting evidence
	1 low risk of bias cohort [21]	Conflicted$
Area/size of the hip joint			Conflicting evidence
	1 low risk of bias cohort [21]	Conflicted$$
C-terminal telopeptide of collagen type II (CTX-II)			Conflicting evidence
	2 low risk of bias cohorts [53, 63] 1 cohort [59]	Positive, no Positive
Hyaluronic acid (HA)			Conflicting evidence
	2 low risk of bias cohorts [53, 63] 1 cohort [23]	Positive, no No
Atrophic bone response (no osteophytes present)			Conflicting evidence
	1 low risk of bias cohort [47] 3 cohorts [25, 50, 65]	No Positive, positive, no
Subchondral cysts			Conflicting evidence
	1 low risk of bias cohort [47] 1 cohort [33]	Positive No
Decrease in joint space width at baseline			Conflicting evidence
	1 low risk of bias cohort [32] 2 cohorts [25, 60]	Positive No, positive
Superior or (supero) lateral migration of the femoral head			Conflicting evidence
	2 low risk of bias cohorts [32, 47] 2 cohorts [25, 50]	Positive, no No, positive
Higher K-L grade at baseline			Conflicting evidence
	4 cohorts [33, 50, 60, 65]	No, positive, positive, no
Acetabular index (Horizontal toit externe angle)			Conflicting evidence
	2 cohorts [20, 65]	Conflicted$$$, no
Wiberg’s center edge angle (CEA)			Conflicting evidence
	2 cohorts [20, 65]	No, negative

^$BMC of superior (p = 0.009) and medial (p = 0.019) quart femoral head, arc regions 2–4 (p = 0.02, 0.001, 0.003, respectively), and the acetabular arc was higher in patients with progression than without progression. BMC of the femoral neck (p = 0.17), intertrochanteric area (p = 0.9), trochanteric area (p = 0.6), and inferior (p = 0.08) and lateral (p = 0.06) quart femoral head and arc region 1 (p = 0.19) of acetabular arc was not significantly different between patients with or without progression

^$$The area/size of superior (p = 0.002), medial (p = 0.002), inferior (p = 0.003), and lateral (p = 0.003) femoral head and of arc regions 2–4 (p = 0.007, 0.001 and 0.005 respectively) of acetabular arc was higher in patients with progression than without progression. The area/size of the femoral neck (p = 0.6), intertrochanteric area (p = 0.16), trochanteric area (p = 0.4), and arc region 1 (p = 0.2) of the acetabular arc was not significantly different between patients with progression and without progression.

^$$$A statistically significant association was found between the acetabular index and progression defined as ≥ 1 increase in joint space narrowing; however, no statistically significant association was found between the acetabular index and progression defined as ≥ 1 increase in K-L grade