Table 4 Significant Prognostic Factors identified in all included studies

¹

Balague [12]

Multivariate analysis (stepwise logistic regression)

"Recovery" (composite score including pain, disability & muscle strength)

Recovery defined as:

ODI Score ≤ 20

VAS pain ≤ 15

Normal muscle strength test (score 5)

Positive neurological examination

(Neurotot)

OR 4.3

(95%CI; 1.37, 13.28)

It is unclear whether the odds ratio given is crude or adjusted.

²

Beauvais [13]

Recovery and failure groups compared using Fishers test, Chi squared test or Wilcoxon test

"Recovery"

Complete = return to usual work/activities, little or no analgesia

Partial = residual pain, frequent analgesic use, complete or partial return to work, limited athletic activities

Failure = persistent pain, continuous analgesic use, unable to return to work

Hospital admission because of severity of sciatic pain

Not reported

³

Carragee [14]

Multivariate analysis (multiple logistic regression)

Composite measure of overall outcome comprising sum of scores on 0-10 scale for self-reported pain, medication use, activity restriction and satisfaction, total divided by 4 to give outcome score

> 6 = good

≤6 = poor

Larger ratio of disc to remaining canal (in conservatively treated patients)

R = 0.50

Shorter duration of symptoms

Absence of litigation

Younger age

Not reported

Data from surgically and non-surgically treated patients analysed separately. Only data from conservatively treated patients presented

⁴

Hasenbring [15]

Multivariate regression analysis

Pain Intensity

Self report

8 point scale

Lesser degree of disc displacement

Scoliosis

High score for non-verbal pain behaviour Low score for direct search for social support

Tendency to ignore pain experience

Poor ability to imagine coping with the pain

Low social status

β = -0.32

β = 0.15

β = 0.31

β = -0.35

β = 0.29

β = -0.20

β = -0.17

Pain intensity was the only outcome studied.

73 (65.8%) underwent surgical treatment but the analysis adjusted for treatment which was not found to be a significant predictor in this study.

⁵

Jensen [16]

Multivariate analysis adjusted for age, sex and treatment

"Recovery" (composite score including pain on 11 point VRS & disability on RMDQ)

Recovery defined as:

Pain score < 1 & RMDQ ≤ 3

Broad based disc protrusion

Disc extrusion

Male gender

Absence of canal stenosis (males only)

OR 13.6

(95% CI; 1.9, 95.4)

OR 10.6

(95% CI; 1.9, 58.7)

OR 2.6

(95% CI; 1.3, 5.0)

OR 4.2

(95% CI; 1.2, 14.7)

⁶

Komori [17]

Non-parametric methods (not further specified)

Outcome defined according to residual self-reported symptoms and disability on 3 point scale (poor, fair, good)

Smaller herniated disc

Greater symptom severity at initial assessment

Not reported

The findings of this study should be interpreted with caution due to poor methodological quality

⁷

Miranda [19]

Multivariate logistic regression

Outcome defined as persistence of pain based on self report of sciatic pain

Persistence = sciatica pain on >30 days/year in 2 consecutive years (1994 & 1995) on modified NMQ)

Poor job satisfaction

Ex-smoker

Jogging

OR 2.8

(95% CI; 1.2,6.7)

OR 2.3

(95% CI; 1.3,4.3)

OR 3.9

( 95% CI;1.4,10.7)

Diagnosis of sciatica based on self-reported symptoms only

⁸

Vroomen [18]

Multivariate logistic regression

Poor outcome defined as absence of any improvement at 3 months based on self-reported change in symptoms

Duration of pain > 30 days

Positive SLR

OR 10

(95%CI;2.5,33.3)*

OR 2.5

(95%CI;1.25,20)* *

see footnote

Patients undergoing eventual surgery excluded from this analysis.

Follow up period only 3 months.