- •Smoking is a modest risk factor for lumbar radicular pain and clinically verified sciatica.
- •Smoking cessation appears to reduce, but not entirely eliminate, the excess risk.
- •The association between smoking and lumbar radicular pain or clinically verified sciatica does not differ between men and women.
Inclusion and Exclusion Criteria
- Armijo-Olivo S.
- Stiles C.R.
- Hagen N.A.
- Biondo P.D.
- Cummings G.G.
Higgins J, Green S. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. The Cochrane Collaboration; 2009 [updated March 2011]. Available at: www.cochrane-handbook.org. Accessed July 2015.
|Characteristic||Past Smoking||Current Smoking||Ever Smoking|
|Sample||OR||95% CI||P-Value||Sample||OR||95% CI||P-Value||Sample||OR||95% CI||P-Value|
|Adjustment for publication bias||1.09||0.94-1.27||1.37||1.21-1.57||1.31||1.18-1.45|
Methodological Quality of Included Studies
Smoking and Sciatica
Heterogeneity and Publication Bias
|Search||Query||No of Items Found|
|#1||Smoking[Mesh] OR smoking[Text Word] OR tobacco[Mesh] OR tobacco[Text Word] OR tobacco products[Mesh] OR cigarette[Text Word] OR cigar[Text Word] OR pipe[Text Word] OR smoke[Mesh] OR smoke[Text Word] OR smok*[Text Word] OR tobacco use disorder[Mesh] OR nicotine[Mesh] OR nicotine[Text Word] OR life style[Mesh] OR life style[Text Word] OR risk factors[Mesh] OR risk factor[Text Word]||934,614|
|#2||Sciatica[Mesh] OR sciatica[Text Word] OR intervertebral disk displacement[Mesh] OR intervertebral disk displacement[Text Word] OR lumbar radicular pain[Text Word] OR sciatic pain[Text Word] OR sciatic neuropathy[Mesh] OR sciatic neuropathy[Text Word] OR sciatic syndrome[Text Word] OR lumbosciatic syndrome[Text Word] OR lumbosacral radicular syndrome[Text Word] OR disc herniation[Text Word] OR herniated lumbar disc[Text Word] OR prolapsed lumbar disc[Text Word] OR disc protrusion[Text Word] OR herniated nucleus pulposus[Text Word] OR spinal diseases[Mesh] OR spinal diseases[Text Word] OR back pain[Mesh] OR back pain[Text Word] OR back disorders[Text Word]||135,150|
|Final||#1 AND #2||6006|
|Type of Bias||Criteria Definition||Classification (Potential for Bias)|
|Selection bias||Sampling method of the study population, representativeness (response rate, difference between responders and nonresponders, investigate and control of variables in case of difference between responders and nonresponders)||Low: Target population defined as representative of the general population or subgroup of the general population (specific age group, women, men, specific geographic area, and specific occupational group) and response rate is 80% or more.|
Moderate: Target population defined as somewhat representative of the general population, a restricted subgroup of the general population, response rate 60%-79%.
High: Target population defined as “self-referred”/ volunteers, or response rate <60%.
|Performance bias||Valid and reliable assessment of exposure|
Exposure assessors blinded to outcome status
|Low: Current smokers compared with never smokers, and former smokers compared with never smokers. Moderate: Current smokers compared with never or former smokers, or current and former smokers combined in a single group.|
|Detection bias||Clear definition of outcome|
Standard method for outcome assessment
Outcome assessors blinded to exposure status
|Low: Clinical diagnosis of sciatica.|
Moderate: Self-reported physician-diagnosed sciatica or using a validated questionnaire.
|Confounding||Matching 2 groups|
|Low: Controlled for most of confounding factors.|
Moderate: Controlled for few confounding factors, particularly age and sex.
High: Not controlled for both age and sex, or controlled for two or fewer confounding factors.
|Attrition bias||Withdrawals and dropout rates|
Size of missing data
|Low: Follow up participation rate of 80% or higher, or missing data of <20%.|
Moderate: Follow-up participation rate of 60%-79%, or missing data of 20%-40%.
High: Follow-up participation rate of <60%, or missing data of more than 40%.
|First Author and Year of Publication||Country||Study Population||Age Range (Years)||Sex||Sample Size (in Analysis)||Smoking||Outcome||Quality Assessment: Risk of bias|
|Results||Adjustment for Other Covariates|
| Karjalainen, 2013|
|Finland||Adolescent||18||Both||1987||Smokers vs never smokers, pack-years||Sciatic pain during the past 12 months with no consultation or pain medication (mild sciatica), sciatic pain required pain medication or consultation with a physician (severe sciatica)||Moderate||Low||Moderate||Low||Moderate||OR of mild or severe sciatica 0.93 (CI, 0.57-1.52)||Sex, BMI, physical activity, sedentary behavior, physical workload and low back pain at age 16 y|
| Korovessis, 2012|
|Greece||General population||20 years or older. 60.5% were younger than 46||Both||674 (254 men and 420 women)||Smokers vs nonsmokers||Low back pain radiating to the posterior surface of the leg during the past 6 months||Moderate||Moderate||Moderate||Moderate||Low||31.7% of smokers and 20.9% of nonsmokers had sciatic pain.|
Estimated unadjusted prevalence ratio 1.515 (CI, 1.16-1.97).
Adjusted OR 2.1 (CI, 1.4-3.1)
|Age, sex, marital status, and work status|
| Leino-Arjas, 2008|
|Finland||General population||30 years or older||Both||5644 (2574 men and 3070 women)||Never smokers; past smokers; current smokers, pack-years ≤20; and current smokers, pack-years >20||Physician diagnosed sciatica||Low||Low||Low||Moderate||Low||Estimated unadjusted prevalence ratio for past smoking 1.71 (CI, 0.83-3.51) for men, 1.08 (CI, 0.62-1.89) for women, and 1.39 (CI, 0.92-2.10) for men and women combined.|
Estimated unadjusted prevalence ratio for current smoking 2.08 (CI, 1.01-4.30) for men, 1.04 (CI, 0.55-1.98) for women, and 1.59 (CI, 1.03-2.44) for men and women combined.
Estimated unadjusted prevalence ratio for ever smoking 1.867 (CI, 0.94-3.71) for men, 1.064 (CI, 0.64-1.75) for women, and 1.34 (CI, 0.97-1.85) for men and women combined.
Adjusted OR for past smoking 1.58 (CI, 0.78-3.23) for men, 1.12 (CI, 0.64-1.96) for women, and 1.28 (CI, 0.82-1.98) for men and women combined.
Adjusted OR for current smoking 2.29 (CI, 1.26-4.15) for men, 1.22 (CI, 0.63-2.37) for women, and 1.73 (CI, 1.11-2.69) for men and women combined.
Adjusted OR for ever smoking 1.965 (CI, 1.24-3.10) for men, 1.16 (CI, 0.757-1.780) for women, and 1.484 (CI, 1.086-2.028) for men and women combined.
|Age and sex|
| Younes, 2006|
|Tunisia||General population||Age range 15-99, mean age 36.1 ± 16.7||Both||4380 (2221 men and 2159 women)||Smokers vs nonsmokers||Physician diagnosed sciatica during past 12 months||Low||Moderate||Low||High||Low||The prevalence of smoking was 47.4% in those with sciatica and 18.5% in those free from sciatica.|
Estimated prevalence ratio 2.56 (CI, 2.05-3.18)
| Violante, 2004|
|Italy||Nurses||Mean age 35.7 ± 8.5||Women||858||Current or past smokers vs never smokers||Self-reported instrumentally diagnosed herniation of a lumbar disc||Moderate||Moderate||Moderate||Low||Low||Estimated unadjusted prevalence ratio 1.034 (CI, 0.745-1.437).|
Adjusted OR 0.95 (CI, 0.49-1.85)
|Age, BMI, motherhood, scoliosis, trauma or fractures of spine or pelvis, sport, work environment / job satisfaction, other diagnosed spine pathologies, coping strategies, stress related psychosomatic symptoms, and depression-related tendencies|
| Kostova, 2001|
|Bulgaria||Workers of a fertilizer plant||Not reported||Both||895||Current smokers vs never or past smokers. Worker who had smoked more than 20 years compared with those smoked less than 20 years and daily consumption of more than 20 cigarettes compared with 20 or less.||Clinically defined lumbosacral radicular syndrome||Moderate||Moderate||Low||High||Low||Estimated prevalence ratio 0.63 (CI, 0.44-0.92) for current smokers vs never or past smokers.|
Estimated prevalence ratio 1.87 (CI, 1.20-2.91) for individuals who had smoked for more than 20 years vs smoked <20 years
| Heliövaara, 1991|
|Finland||General population||30-64||Both||5673 (2727 men and 2946 women)||Never, past, or current smokers, and number of cigarettes smoked per day||Physician diagnosed sciatica||Low||Low||Low||Low||Low||Estimated unadjusted prevalence ratio 1.09 (CI, 0.82-1.45) for past smoking, 1.01 (CI, 0.73-1.40) for cigars, pipes or 1-19 cigarettes per day, and 1.24 (CI, 0.87-1.77) for 20 or more cigarettes per day.|
Estimated unadjusted prevalence ratio 1.11 (CI, 0.87-1.41) for current smoking and 1.10 (CI, 0.92-1.32) for ever smoking.
Adjusted OR 0.9 (CI, 0.6-1.3) for past smoking, 0.9 (CI, 0.6-1.3) for cigars, pipes or 1-19 cigarettes/day and 1.1 (CI, 0.7-1.6) for 20 or more cigarettes per day.
Estimated adjusted OR 0.988 (CI, 0.745-1.311) for current smoking and 0.957 (CI, 0.762-1.202) for ever smoking
|Age, sex, body height, prior traumatic back injury, physical work load, driving motor vehicles, occupational mental stress, body mass index and alcohol consumption|
|Case control studies|
| Chiang, 2014|
|Taiwan||Cases were patients with lumbar disc herniation and controls were a random sample of other inpatients||Mean age 39 ± 18.4||Both, 69% were men||822 (391 cases and 431 controls). Of cases 264 had lumbar discectomy||Current or past smokers vs never smokers. Number of cigarettes smoked per day, number of years smoked, and pack-years||Hospitalization due to lumbar disc herniation confirmed by CT or MRI.|
Surgery due to lumbar intervertebral disc herniation
|Moderate||Moderate||Low||Moderate||Low||Unadjusted 1.82 (CI, 1.37-2.43) for hospitalization, and 1.63 (1.21-2.21) for surgery.|
Adjusted OR 1.51 (CI, 1.09-2.10) for hospitalization, and 1.76 (1.26-2.47) for surgery.
Estimated unadjusted OR 1.73 (CI, 1.25-2.38) and estimated adjusted OR 1.63 (CI, 1.13-2.34) for hospitalization or surgery.
A dose-response relation between pack-years and number of years smoked, and both outcomes
|Sex, age, height, body weight, and BMI|
| Zhang, 2013|
|China||Cases were patients with lumbar disc herniation and controls were a random sample of other inpatients or participants of medical examinations||Mean age 46.2 ± 13.1 for cases and 47.4 ± 12.9 for controls||Both||260 (128 cases and 132 controls)||Current or past smokers vs never smokers||Lumbar disc herniation confirmed by CT or MRI||Moderate||Moderate||Low||Moderate||Low||OR 1.286 (CI, 0.770-2.145)||Matched by age, sex, race, and living area|
| Schumann, 2010|
|Germany||Patients with lumbar disc herniation and population controls||25-70||Both||1458 (561 patients and 897 controls). 736 men and 722 women||Current or past smokers vs never smokers, pack-years||In- or outpatients who received treatment due to lumbar disc herniation (confirmed by CT or MRI) with radiculopathy and with sensory or motor deficits||High||Moderate||Low||Moderate||Low||Estimated unadjusted OR 1.33 (CI, 0.98-1.81) for men, 1.27 (CI, 0.94-1.72) for women, and 1.30 (CI, 1.05-1.61) for men and women combined.|
Adjusted OR 1.18 (CI, 0.92-1.52) for men, 1.16 (CI, 0.90-1.50) for women, and 1.17 (CI, 0.98-1.40) for men women combined
|Sex-specific adjusted for age, region, and cumulative physical workload|
| Zhang, 2009|
|China||Patients hospitalized due to lumbar disc disorders, and controls a random sample of inpatients or participants of medical examination||Mean age 45 for cases and 47 for controls||Both||4180 (2010 cases and 2170 controls)||Current or past smokers vs never smokers||Hospitalization due to lumbar disc disorders||Moderate||Moderate||Low||Moderate||Low||41.1% of cases and 31.2% of controls were smokers.|
Estimated OR 1.54 (CI, 1.36-1.75)
|Matched by age, sex, race, and living area|
| Saftic, 2006|
|Croatia||A random sample from nine villages. Cases were patients with lumbar discectomy due to lumbar intervertebral disc herniation, and controls were a random sample of healthy individuals||18 or older||Both||335 (67 cases and 268 controls)||Current or past smokers vs never smokers||Surgery due to lumbar intervertebral disc herniation||Low||Moderate||Low||Moderate||Low||Estimated OR 0.99 (CI, 0.57-1.69) for ever smoking||Matched by age, sex, and village of residence or immigrant status|
| An, 1994|
|USA||Cases were patients with lumbar discectomy due to disc herniation, and controls were other medical or surgical inpatients||Age range 16-78, mean age 44.5 for both groups||Both||368 (163 cases and 205 controls). 228 men and 140 women||Never, past, or current smokers||Lumbar discectomy due to intervertebral disc herniation||Moderate||Low||Low||Moderate||Low||Estimated OR 1.25 (CI, 0.70-2.23) for past smoking, 3.14 (CI, 1.92-5.13) for current smoking, and 2.21 (CI, 1.45-3.36) for ever smoking.|
Estimated OR for ever smoking 3.41 (CI, 1.97-5.91) for men and 1.14 (CI, 0.58-2.23) for women
|Matched by age and sex|
| Heliövaara, 1987|
|Finland||General population||20-59||Both||2742 (592 cases, 2150 controls). 1672 men and 1070 women||Current smokers vs nonsmokers||Hospitalization due to herniated lumbar disc or sciatica||Low||Moderate||Low||Low||Low||Estimated unadjusted OR of herniated disc 1.36 (CI, 1.00-1.85) and multivariate OR 1.3 (CI, not reported) for men.|
Estimated unadjusted OR of herniated disc or sciatica 1.16 (CI, 0.92-1.47) and multivariate OR 1.0 (CI, not reported) for men.
Estimated unadjusted OR of herniated disc 1.175 (CI, 0.707-1.954) and multivariate OR 1.0 (CI, not reported) for women.
Estimated unadjusted OR of herniated disc or sciatica 1.372 (CI, 0.947-1.987) and multivariate OR 1.4 (CI, not reported) for women.
Estimated unadjusted OR of herniated disc 1.269 (CI, 0.994-1.620) for men and women combined.
Estimated unadjusted OR of herniated disc or sciatica 1.197 (CI, 0.995-1.441) for men and women combined.
Estimated adjusted OR of herniated disc 1.212 (CI, 0.931-1.576) for men and women combined.
Estimated adjusted OR of herniated disc or sciatica 1.10 (CI, 0.90-1.34) for men and women combined
|Cases were matched with controls for age, sex and place of residence.|
Adjusted for occupational group, social class, marital status, number of birth (for women), leisure time physical activity, chronic cough, number of distress symptoms, use of medication, and frequent use of analgesics
| Kelsey, 1984|
|USA||Cases were in- or outpatients with prolapsed lumbar intervertebral disc, or sciatica. Controls were patients admitted to the same hospitals or practices for conditions not related to the spine||Age range 20-64||Both||650 (325 cases and 325 controls)||Never, past, or current smokers||Lumbar disc herniation (165 of 325 cases), or sciatica||Moderate||Low||Low||Moderate||Low||Unadjusted OR 1.0 (CI, 0.6-1.7) for past smoking, and 1.7 (CI, 1.0-2.5) for current smoking.|
Estimated unadjusted OR 1.35 (CI, 0.95-1.90) for ever smoking.
Adjusted OR 1.2 (CI, 1.0-1.4) for current smoking for 10-cigarette increase
|74% of cases were matched with controls for age and sex.|
OR adjusted for driving, lifting objects >11.3 kg >25 times per day while twisting body, knees not bent, and lifting objects >11.3 kg >25 times per day while twisting body, knees bent
| Sørensen 2011|
|Denmark||Occupational population (14 private or public companies)|
A 33-y follow-up
|40-59 at baseline||Men||3831||Never, past, or current smokers||Hospitalization due to herniated lumbar disc disease||Low||Low||Low||Moderate||Low||Estimated unadjusted RR 1.32 (CI, 0.52-3.31) for past smoking, 0.80 (0.34-1.87) for current smoking, and 0.91 (CI, 0.39-2.08) for ever smoking.|
Estimated age-adjusted RR 1.43 (CI, 0.56-3.63) for past smoking, 0.95 (CI, 0.40-2.23) for current smoking and 1.146 (CI, 0.61-2.16) for ever smoking
| Matsudaira, 2013|
|Japan||Occupational population (16 offices of participating organizations).|
A 2-year follow-up
|<40 y 37.6%, 40-49 y. 29.6%, and 50 y or older 32.8%||Both, 88.5% were men||765||Heavy smokers (Brinkmann smoking index 400 or higher) vs nonheavy smokers||Low back pain radiating blow the knee during the follow-up||Moderate||Moderate||Moderate||Moderate||Moderate||Unadjusted OR 1.35 (CI, 0.89-2.03).|
Adjusted OR 1.20 (CI, 0.76-1.88)
|Age and sex|
| Wahlström, 2012|
A 17-year follow-up
|20-65||Men||263,529||Never, past, or current smokers||Hospitalization due to lumbar disc disease||Low||Low||Low||Low||Moderate||Adjusted RR 1.08 (CI, 0.94-1.25) for past smoking and 1.27 (CI, 1.15-1.39) for current smoking, and 1.208 (CI, 1.117-1.308) for ever smoking||Age, occupation, body height, body weight and time period of the diagnosis|
| Kääriä, 2011|
5 to 7 years follow-up
|40-60 at baseline||Both||5261 (1098 men and 4163 women)||Never, past, or current smokers||Low back pain radiating to the calf or the foot during the follow-up||Moderate||Low||Moderate||Low||Low||Estimated unadjusted RR for past smoking 1.24 (CI, 0.79-1.94) for men and 2.34 (CI, 1.45-3.77) for women.|
Estimated unadjusted RR for current smoking 2.01 (CI, 1.32-3.06) for men and 3.50 (CI, 2.23-5.50) for women.
Estimated unadjusted RR for ever smoking 1.58 (CI, 1.08-2.31) for men and 2.87 (CI, 1.91-4.32) for women.
Estimated unadjusted RR 1.670 (CI, 1.204-2.317) for past smoking, 2.601 (CI, 1.912-3.537) for current smoking, and 2.113 (CI, 1.689-2.644) for ever smoking for men and women combined.
Adjusted OR for past smoking 1.00 (CI, 0.73-1.36) for men and 1.06 (CI, 0.90–1.24) for women.
Adjusted OR for current smoking 1.36 (CI, 0.97-1.89) for men and 1.45 (CI, 1.23–1.71) for women.
Estimated adjusted OR for ever smoking 1.154 (CI, 0.919-1.449) for men and 1.234 (CI, 1.100-1.385) for women.
Estimated adjusted OR 1.047 (CI, 0.908-1.207) for past smoking, 1.432 (CI, 1.235-1.660) for current smoking, and 1.218 (CI, 1.099-1.349) for ever smoking for men and women combined
|Age, occupational class, BMI, leisure-time physical activity, pain-related factors, and physical work factors (for men only)|
| Rivinoja, 2011|
A 28-year follow-up
|14 at baseline 42 at the end of follow-up||Both||9016 (4535 males and 4481 females)||Occasional or daily smokers vs never smokers or those smoked less than a few times||Lumbar discectomy due to sciatica||Low||Low||Low||Low||Moderate||Adjusted OR 1.35 (CI, 0.88-2.07) for males, and 1.0 (CI, 0.38-2.60) for females.|
Estimated adjusted OR 1.285 (CI, 0.869-1.899) for males and females combined
|Participation in sports, participation in sports with risk of injury, membership in a sport club, and overweight|
| Mattila, 2008|
A 11.3-year follow-up
|14, 16 or 18 at baseline||Both||57,408 (26,688 boys and 30,719 girls)||Smoking daily vs not daily||Lumbar discectomy||Moderate||Low||Low||Moderate||Low||Age-adjusted HR 1.6 (CI, 1.2-2.2) for males and 0.7 (CI, 0.4-1.2) for females.|
Estimated age-adjusted HR 1.319 (CI, 1.012-1.720) for males and females combined.
HR 1.5 (CI, 1.1-2.2) for males adjusted for age and timing of puberty.
Estimated adjusted HR 1.207 (CI, 0.901-1.619) for males and females combined (a rough estimate)
|Adjusted for age for females and for age and timing of puberty for males|
| Jhawar, 2006|
A 16-year follow-up
|30-55 at baseline||Women||98,407||Never, past, or current smokers, number of cigarettes smoked per day||Self-reported ever physician diagnosed herniated lumbar disc confirmed by CT scan or MRI||Low||Low||Moderate||Low||Low||Age-adjusted RR 1.13 (CI, 1.03-1.23) for past smoking, 1.28 (CI, 1.16-1.40) for current smoking, and 1.20 (CI, 1.12-1.28) for ever smoking.|
Multivariate RR 1.10 (CI, 1.00-1.20) for past smoking, 1.38 (CI, 1.26-1.52) for current smoking, and 1.23 (CI, 1.15-1.31) for ever smoking.
A dose-response relation between number of cigarettes smoked per day and lumbar disc herniation
|Age, BMI, physical exercise, employment status, high cholesterol, hypertension, diabetes, physician visitation within the last year, family history of myocardial infarction before age 60|
| Leino-Arjas, 2006|
|Finland||Metal industry employees.|
A 28-year follow-up
|18-64||Both||530 (345 men and 185 women)||Never, past, or current smokers||Frequent radiating low back pain during the past 12 months||Low||Low||Moderate||Moderate||Moderate||Estimated unadjusted RR for past smoking 2.41 (CI, 1.45-4.02) for men, 1.49 (CI, 0.81-2.72) for women, and 1.76 (CI, 1.23-2.52) for both sexes.|
Estimated unadjusted RR for current smoking 2.22 (CI, 1.30-3.77) for men, 2.19 (CI, 1.40-3.43) for women, and 1.92 (CI, 1.35-2.72) for both sexes.
Estimated unadjusted RR for ever smoking 2.32 (CI, 1.45-3.72) for men, 1.88 (CI, 1.24-2.86) for women, and 1.84 (CI, 1.35-2.50) for both sexes.
Adjusted OR for past smoking 2.85 (CI, 1.45-5.58) for men, 1.78 (CI, 0.63-5.01) for women, and 2.48 (CI, 1.41-4.36) for men and women combined.
Adjusted OR for current smoking 2.12 (CI, 1.06-4.24) for men, 2.71 (CI, 1.13-6.49) for women, and 2.33 (CI, 1.35-4.01) for men and women combined.
Adjusted OR for ever smoking 2.47 (CI, 1.52-4.00) for men, 2.28 (CI, 1.17-4.44) for women, and 2.40 (CI, 1.62-3.55) for men and women combined
|Age, sex and occupational class|
| Kaila-Kangas, 2003|
|Finland||Metal industry employees.|
A 28-year follow-up
|18-64||Both||902||Never, past, or current smokers, pack-years||Hospitalization due to intervertebral disc disorders||Low||Low||Low||Low||Low||Estimated unadjusted RR 1.32 (CI, 0.48-3.57) for past smoking, 2.36 (CI, 1.12-4.96) for current smoking, and 1.99 (CI, 0.97-4.10) for ever smoking.|
Adjusted RR 1.64 (CI, 0.57-4.76) for past smoking, 2.30 (CI, 0.91-5.82) for current smoking 1-9 pack-y, and 3.41 (CI, 1.29-8.98) for current smoking >9 pack-y
Estimated adjusted RR 2.776 (CI, 1.420-5.428) for current smoking, and 2.389 (CI, 1.355-4.211) for ever smoking.
A dose-response relation between pack-years and hospitalization due to disc disorders
|Age, sex, occupational class, strenuous physical work, exercise, BMI, chronic back disorders and stress syndrome|
| Miranda, 2002|
|Finland||Forest industry workers.|
A 1-year follow-up
|Mean age 45||Both||2045||Never, past, or current smokers. Pack-years.||Radiating low back pain longer than 7 days during the past 12 months||High||Low||Moderate||Low||Low||Estimated unadjusted RR 1.33 (CI, 1.10-1.61) for past smoking, 1.51 (CI, 1.24-1.84) for current smoking, and 1.28 (CI, 1.14-1.43) for ever smoking.|
Adjusted OR 1.3 (CI, 0.9-2.0) for past smoking, 1.95 (CI, 1.37-2.78) for current smoking, and 1.64 (CI, 1.25-2.13) for ever smoking.
A dose-response relation between pack-years and sciatic pain
|Age, sex, mental stress, walking, twisting movements of the trunk, working in kneeling or squatting position, and working with hand above shoulder level|
| Manninen, 1995|
A 12-year follow-up
|Age range 45-54 and mean age 49.3 ± 2.8 at baseline||Men||193||Never, past, or current smokers. Pack-years.||Low back pain radiating to the foot during past 12 months||High||Low||Moderate||Low||Moderate||Unadjusted RR 3.74 (CI, 1.21-11.54) for past smoking and 2.96 (CI, 0.91-9.64) for current smoking, and 3.35 (CI, 1.16-9.66) for ever smoking.|
Adjusted OR 13.1 (CI, 2.66-65.1) for past smoking and 9.6 (CI, 1.73-53.0) for current smoking, and 11.33 (CI, 3.52-36.45) for ever smoking.
No dose-response relation between pack-years and sciatic pain
|Age, height, mental stress, BMI, farm production, occupational class and pain in the joints|
| Riihimäki, 1994|
|Finland||Machine operators, carpenters, and office workers.|
A 3-year follow-up
|25-49||Men||1149||Current or past smokers vs never smokers.|
Smoking status was inquired at the follow-up
|Low back pain radiating to the leg. 3-year cumulative incidence of sciatic pain||Low||Moderate||Moderate||Moderate||Low||OR 1.29 (CI, 0.98-1.69)||Occupation, physical exercise, and history of other low back pain|
| Riihimäki, 1989|
|Finland||Concrete reinforcement workers or house painters.|
A 5-year follow-up
|25-54||Men||163||Never, past, or current smokers||5-year cumulative incidence of sciatic pain||Moderate||Low||Moderate||Moderate||Moderate||Unadjusted RR 1.0 (CI, 0.4-2.3) for past smoking and 1.0 (CI, 0.4-2.2) for current smoking.|
Age-adjusted RR 1.0 (CI, 0.4-2.1) for past smoking and 1.0 (CI, 0.5-2.0) for current smoking.
Estimated unadjusted RR 1.0 (CI, 0.54-1.84) for ever smoking.
Estimated age-adjusted RR 1.0 (CI, 0.59-1.70) for ever smoking
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Conflict of Interest: None.
Authorship: RS developed the review protocol, conducted the literature searches and extracted data. RS and KF-H rated the quality of included studies. RS performed the meta-analyses, interpreted the results, and drafted the manuscript. KF-H contributed to the writing of the manuscript. Both authors have approved the final manuscript to be submitted for publication.