Outcome of Surgery for Sciatica - a Comparison of Data From Three National Quality Registries
NCT ID: NCT02889484
Last Updated: 2017-12-05
Study Results
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Basic Information
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COMPLETED
7500 participants
OBSERVATIONAL
2011-01-31
2015-06-30
Brief Summary
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Hypotheses: (i) there are no differences in patient-reported outcome after surgery between these countries, (ii) there are no differences in indications for surgery between these countries and (iii), factors that predict outcome are similar in these countries.
Method of research: By using data from three Nordic national spine registers, we will compare baseline data, indications for surgery and patient reported outcome one year after surgery for lumbar disc herniation. Register based studies have advantages such as large sample sizes, reflecting real life, but they also have limitations such as lower follow-up rates than clinical trials. A non-response analysis will be performed to take this into account.
Detailed Description
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The registers
All registries have the aim of studying outcome after spine surgery. All departments and patients participate voluntarily. At the time of admission, the patient reports data consisting of information on social factors, comorbidity and previous surgery. After surgery, the surgeon records diagnosis and type of surgery performed.
The Swespine Register has included individuals treated with surgery for lumbar disc herniation since 1993. During the last decade, the number of departments participating in the registry has varied between 35 and 41 of the 42 to 45 departments providing spinal surgery services in Sweden. Coverage is approximately 90%. The completeness (number of patients reported to Swespine at the time of surgery) is approximately 80%.
The Norwegian Spine register, NORspine, is based on experiences from the Swespine register and previous validation studies from a local clinical registry, and was founded in 2007. In total 36 of 40 centers performing lumbar spine surgery in Norway report to NORspine. Coverage is approximately 90%. The completeness is approximately 65%.
The Danish spine register, DaneSpine, is based on Swespine and was acquired by the Danish Spine Society from the Swedish Society of Spinal Surgeons in 2009 and has successively been implemented. In total 17 of 19 centers performing lumbar spine surgery in Denmark report to DaneSpine. Coverage is approximately 90%. The completeness is approximately 60%.
Quality assurance
As for all studies, there is a risk that loss to follow-up may bias the results. Solberg et al. (2011) studied 633 patients, who were operated on for degenerative disorders of the lumbar spine in Norway, and found that a loss to follow-up of 22% would not bias conclusions about overall treatment effects. There were no indications of worse outcomes in the non-responders group. In a similar one-center study of the DaneSpine. Højmark et al. (2016) found that a loss to follow-up of 12% at did not seem to bias the conclusions that can be drawn from DaneSpine at that center. Preliminary data indicates that predictors of outcome after lumbar disc herniation surgery are comparable with data in a study with a very high follow-up rate and with the Swespine register.
Data handling
Anonymized individual level data from all three registers will be pooled in one database. The cohort will be divided by country for comparisons.
Missing data and out of range data
In case of missing data case exclusion analysis by analysis, will be used. Out of range data will be deleted.
Analysis
The data will be cleaned by excluding patients with missing or incorrect date of surgery, missing date for follow-up, previous lumbar spine surgery and surgery other than discectomy only.
After data cleaning, we aim to perform blinded statistical analyses, in which the independent statistician performing the analyses is unaware of group belonging (i.e. country). The code will not be broken until the analyses and interpretations have been performed.
Comparisons of indications for surgery
Analysis of baseline data will include age at surgery, sex, anthropometrics, number of smokers, Oswestry Disability Index, numeric rating scale leg pain, numeric rating scale back pain, EQ-5D, number on sick leave, employment status, and duration of leg and back pain and presented as mean (SD), mean (95% confidence interval), or number (%).
Variables will be analyzed by analysis of variance, Chi-square or logistic regression tests. Data will be presented as crude (unadjusted) data to elucidate any differences between the countries.
Comparisons of outcome
Comparisons of the change of the outcome variables from baseline to 1 year, as well as comparisons of the actual value at 1 year will be performed. Analysis of covariance (ANCOVA), Chi-square or logistic regression tests will be used and the crude (unadjusted) data will be presented.
The baseline variables will be used as covariates in the ANCOVA and the adjusted data presented. Additionally, the results from the ANCOVA will be compared with results from propensity score matching or ANCOVA with the propensity score as a covariate.
Non-response analysis
A non-response analysis will be performed comparing all available baseline variables between those that responded to the 1 year follow-up with those that did not respond.
Sample size
A study of similar character has never been performed before. Due to the nature of the study, the sample size is not formulated in the guise of power, risk level, or clinical difference. The number of patients participating in the study is estimated to 7500. The sample is so large that differences in the Oswestry Disability Index of as low as 2 points may be detected (power 90%, significance level 5%), but in the interpretation the minimal important difference of 10-15 points in the Oswestry Disability Index often referred to has to be taken into account.
Conditions
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Study Design
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COHORT
PROSPECTIVE
Study Groups
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Disc hernia patients treated in Sweden
Individuals undergoing lumbar disc hernia surgery and included in the Swespine register
Lumbar disc hernia surgery
Disc hernia patients treated in Norway
Individuals undergoing lumbar disc hernia surgery and included in the NORspine register
Lumbar disc hernia surgery
Disc hernia patients treated in Denmark
Individuals undergoing lumbar disc hernia surgery and included in the Danespine register
Lumbar disc hernia surgery
Interventions
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Lumbar disc hernia surgery
Other Intervention Names
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Eligibility Criteria
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Inclusion Criteria
Exclusion Criteria
18 Years
65 Years
ALL
No
Sponsors
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Karolinska Institutet
OTHER
Responsible Party
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Paul Gerdhem
MD, PhD, Assoc Prof
Principal Investigators
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Paul Gerdhem, MD, PhD
Role: PRINCIPAL_INVESTIGATOR
Karolinska University Hospital and Karolinska Institutet, K54, Huddinge, SE-141 86 Stockholm, Sweden
References
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Hojmark K, Stottrup C, Carreon L, Andersen MO. Patient-reported outcome measures unbiased by loss of follow-up. Single-center study based on DaneSpine, the Danish spine surgery registry. Eur Spine J. 2016 Jan;25(1):282-286. doi: 10.1007/s00586-015-4127-3. Epub 2015 Jul 25.
Solberg TK, Sorlie A, Sjaavik K, Nygaard OP, Ingebrigtsen T. Would loss to follow-up bias the outcome evaluation of patients operated for degenerative disorders of the lumbar spine? Acta Orthop. 2011 Feb;82(1):56-63. doi: 10.3109/17453674.2010.548024. Epub 2010 Dec 29.
Other Identifiers
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1
Identifier Type: -
Identifier Source: org_study_id