Back pain is also improved by lumbar disc herniation surgery

Figures & data

Table 1. Preoperative data in patients with both pre- and 1-year postoperative numeric rating scale (NRS) back pain data (n = 14,097) and in those with missing 1-year NRS back pain data (n = 5,718). Data are presented as numbers (n), proportions (%), or mean (standard deviation)

Factor	n	Patients with pre- and postoperative NRS back pain data	Patients with incomplete NRS back pain data
Mean age (SD)	14,097	43 (11)	41 (10)
Male sex (%)	14,097	55	61
Smokers (%)	13,975	19	25
Short Form-36 (SD)	13,930	47 (28)	45 (27)
NRS back pain (SD)	14,097	4.7 (2.9)	5.0 (2.9)
NRS leg pain (SD)	14,064	6.7 (2.5)	6.7 (2.5)
Duration of back pain (%)	13,191
0–3 months		13	11
3–12 months		50	49
12–24 months		17	17
> 24 months		20	23
Duration of leg pain (%)	13,877
0–3 months		17	15
3–12 months		54	53
12–24 months		15	16
> 24 months		14	15

Table 2. Numeric rating scale 0–10 for back pain (N_back) and leg pain (N_leg) at baseline, 1 year after surgery, changes by surgery, and the proportion of patients with improvement ≥ MCID in pain (≥ 2.5 for N_back and ≥ 3.5 for N_leg)

		Mean NRS (SD)		Changes in NRS (CI)		Proportion with improvement
Factor	n	preoperatively	at 1 year	absolute	relative (%)	≥ MCID (%)	p-value
All patients
Nback	14,097	4.7 (2.9)	2.5 (2.7)	–2.2 (–2.1 to –2.2)	–47 (–45 to –47)	43	< 0.001
Nleg	14,023	6.7 (2.5)	2.1 (2.7)	–4.5 (–4.5 to –4.6)	–67 (–67 to –69)	71
Patients with preoperative back and/or leg pain ≥ MCID
Nback	9,975	6.2 (2.0)	3.0 (2.8)	–3.2 (–3.1 to –3.3)	–52 (–50 to –53)	60	< 0.001
Nleg	12,268	7.4 (1.7)	2.2 (2.8)	–5.1 (–5.1 to –5.2)	–69 (–69 to –70)	79

n — the number of patients who had answered this specific question;

SD —standard deviation; CI — 95% confidence intervals.

Table 3. Negative binomial regression model presenting adjusted relative risk (RR) for different preoperative factors in respect of reaching improvement ≥ MCID in back pain in 9,674 patients with complete data

Factor	Mean RR (95% CI)
Age	1.0 (0.99–1.0)
Male (reference: female)	0.97 (0.91–1.0)
Smoker (reference: non-smoker)	0.9 (0.8–0.9) ^a
Short Form-36	1.0 (0.99–1.0)
Duration of back pain (reference: > 24 months)
0–3 months	1.4 (1.3–1.6) ^a
3–12 months	1.3 (1.2–1.4) ^a
12–24 months	1.1 (1.0–1.3) ^a

To be included in this model, patients had to have N_back ≥ 2.5 at baseline. For continuous variables results are presented as RR per unit of change in the independent variable and for categorical variables compared with a reference category.

^a Statistically significant.

Table 4. Negative binomial regression model presenting adjusted relative risk (RR) for different preoperative factors in respect of reaching improvement ≥ MCID in leg pain in 11,957 patients with complete data

Factor	Mean RR (95% CI)
Age	1.0 (1.0–1.0) ^a
Male (reference: female)	0.95 (0.90–1.0)
Smoker (reference: non-smoker)	0.9 (0.8–0.95) ^a
Short Form-36	1.0 (1.0–1.0)
Duration of back pain (reference: > 24 months)
0–3 months	1.3 (1.2–1.5) ^a
3–12 months	1.2 (1.1–1.3) ^a
12–24 months	1.1 (0.99–1.2)

To be included in this model, patients had to have N_leg ≥ 3.5 at baseline. For continuous variables results are presented as RR per unit of change in the independent variable and for categorical variables compared with a reference category.

^a Statistically significant.