Table 1.

Previously identified candidate predictors of failure of nonoperative treatment for lumbosacral radiculopathy and characteristics of the studies in which they were identified*

Prognostic factor	Clinical setting	Country	Duration of symptoms†	Followup	Conflicting studies?ǂ	Supporting studies?
Predictors of treatment failure defined as subsequent surgery
Initial leg pain intensity [30]	Primary care	Netherlands	Acute	6 months	No	Yes [20]
Initial disability [20]	Specialty care	Netherlands	Subacute	1 year	No	No
Duration of symptoms [28]	Specialty care	France	Acute	11–24 months	Yes [30]	No
Prior low back pain [30]	Primary care	Netherlands	Acute	6 months	No	No
Positive straight leg raise test (SLR) [28]	Specialty care	France	Acute	11–24 months	Yes [20, 30]	Yes [31]§
Positive crossed SLR [30]	Primary care	Netherlands	Acute	6 months	No	No
Positive femoral stretch test [30]	Primary care	Netherlands	Acute	6 months	No	Yes [31]§
Predictors of treatment failure defined as persistent leg pain at followup
Initial leg pain intensity [11]	Specialty care	Norway	Acute/chronic	1–2 years	Yes [27]	No
Initial back pain intensity [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Female sex [12]	Specialty care	Denmark	Acute/chronic	14 months	Yes [17, 27]	No
Duration of symptoms [23]	Specialty care	United States	Subacute/chronic	2–4 years	Yes [11]	No
Smoking [11]	Specialty care	Norway	Acute/chronic	1–2 years	Yes [17]	No
Medical comorbidities [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Workers compensation [3]	Specialty care	United States	Acute/chronic	4 years	Yes [4]	Yes [2]
Muscle weakness (any) [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Herniation morphology [12]||	Specialty care	Denmark	Acute/chronic	14 months	No	No
Predictors of treatment failure defined as persistent disability at followup
Initial disability [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Initial back pain intensity [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Female sex [12]	Specialty care	Denmark	Acute/chronic	2 years	No	No
Duration of symptoms [23]	Specialty care	United States	Subacute/ chronic	2–4 years	No	Yes [11]
Smoking [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Medical comorbidities [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Prior low back pain [11]	Specialty care	Norway	Acute/chronic	2–4 years	No	No
Workers compensation [3]	Specialty care	United States	Acute/chronic	4 years,	Yes [4]	Yes [2]
Herniation morphology [12]||	Specialty care	Denmark	Acute/chronic	14 months	No	No
Abnormal tendon reflexes [11]	Specialty care	Norway	Acute/chronic	1–2 years	No	No
Predictors of treatment failure defined as participant-reported lack of recovery at followup
Age [14]	Specialty care	Netherlands	Subacute	5 year	Yes [21, 31]	No
Female sex [21]	Specialty care	Netherlands	Subacute	1 year	Yes [31]	No
Duration of symptoms [31]	Primary care	Netherlands	Acute	3 months	No	No
Smoking [21]	Specialty care	Netherlands	Subacute	1 year	Yes [31]	No
Workers compensation [3]	Specialty care	United States	Acute/chronic	5–10 years	No	No
Positive SLR [31]	Primary care	Netherlands	Acute	3 months	Yes [21]	No
Positive femoral stretch test [31]	Primary care	Netherlands	Acute	3 months	No	No
Foraminal herniation [33]	Primary care	Netherlands	Acute	3 months	No	No

* All associations between candidate predictors and outcomes refer to positive associations, except for those studies cited under Conflicting studies; ^†acute signifies duration of symptoms ≤ 12 weeks, whereas subacute signifies duration of 6–12 weeks; ^ǂConflicting studies refers to those in which no statistically significant association with an outcome was found or where a statistically significant association was found with a negative association (in the opposite direction than expected); ^§subsequent surgery was also included in a composite outcome; ^||disc extrusions predicted lower pain intensity and disability; sequestrations and extrusions were collinear.