Surgically Treated Degenerative Lumbar Spine Diseases in Twins.

BACKGROUND: There is growing evidence to suggest a potential genetic component underlying the development and progression of lumbar spine diseases. However, the heritability and the concordance rates for the phenotypes requiring surgery for the common spine diseases lumbar spinal stenosis (LSS) and lumbar disc herniation (LDH) are unknown. The aim of this study was to determine the heritability and the concordance rates for LSS and LDH requiring surgery by studying monozygotic (MZ) and dizygotic (DZ) twin pairs. METHODS: Patients between 18 and 85 years of age who underwent surgery for LSS or LDH between 1996 and 2022 were identified in the national Swedish spine registry (LSS: 45,110 patients; LDH: 39,272 patients), and matched with the Swedish Twin Registry to identify MZ and DZ twins. Pairwise and probandwise concordance rates, heritability estimates, and MZ/DZ concordance ratios were calculated. RESULTS: We identified 414 twin pairs (92 MZ and 322 DZ pairs) of whom 1 or both twins underwent surgery for LSS. The corresponding number for LDH was 387 twin pairs (118 MZ and 269 DZ pairs). The probandwise concordance rate for LSS requiring surgery was 0.25 (26 of 105) (95% confidence interval [CI], 0.14 to 0.34) for MZ twins and 0.04 (12 of 328) (95% CI, 0.01 to 0.07) for DZ twins. The corresponding values for LDH requiring surgery were 0.03 (4 of 120) (95% CI, 0 to 0.08) and 0.01 (4 of 271) (95% CI, 0 to 0.04), respectively. The probandwise MZ/DZ concordance ratio was 6.8 (95% CI, 2.9 to 21.5) for LSS and 2.3 (95% CI, 0 to 8.9) for LDH. The heritability was significantly higher in LSS compared with LDH (0.64 [95% CI, 0.50 to 0.74] versus 0.19 [95% CI, 0.08 to 0.35]). CONCLUSIONS: Our findings suggest that genetic factors may play an important role in the risk of developing LSS requiring surgery, whereas heredity seems to be of less importance in LDH requiring surgery. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Surgically treated degenerative disk disease in twins.

PURPOSE: Previous studies have suggested that genetic factors are important in the development of degenerative disk disease (DDD). However, the concordance rates for the phenotypes requiring surgery are unknown. The purpose of this study was to determine the concordance rates for DDD requiring surgery by studying monozygotic (MZ) and dizygotic (DZ) twin pairs. METHODS: Patients, aged between 18 and 85 years, operated for DDD between 1996 and 2022 were identified in the national Swedish spine register (Swespine) and matched with the Swedish twin registry (STR) to identify MZ and DZ twins. Pairwise and probandwise concordance rates were calculated. RESULTS: We identified 11,207 patients, 53% women, operated for DDD. By matching the Swespine patients with the STR, we identified 121 twin pairs (37 MZ and 84 DZ) where one or both twins were surgically treated for DDD. The total twin incidence for operated DDD was 1.1%. For DDD requiring surgery, we found no concordant MZ pair and no concordant DZ pair where both twins were operated for DDD. When we evaluated pairs where at least one twin was operated for DDD, we found two concordant MZ pairs (the co-twins were operated for spinal stenosis) and two  concordant DZ pairs (one co-twin operated for spinal stenosis and one (co-twin operated for disk herniation). CONCLUSIONS: Our findings suggest that genetic factors are probably not a major etiologic component in most cases of DDD requiring surgery. The findings of this study can be used for counseling patients about the risk for requiring DDD surgery.

Associations between future health expectations and patient satisfaction after lumbar spine surgery: a longitudinal observational study of 9929 lumbar spine surgery procedures.

OBJECTIVE: This study aimed to investigate the associations between general health expectations and patient satisfaction with treatment for the two common spine surgery procedures diskectomy for lumbar disk herniation (LDH) and decompression for lumbar spinal stenosis (LSS). DESIGN: Register study with prospectively collected preoperative and 1-year postoperative data. SETTING: National outcome data from Swespine, the national Swedish spine register. PARTICIPANTS: A total of 9929 patients, aged between 20 and 85 years, who were self-reported non-smokers, and were operated between 2007 and 2016 for one-level LSS without degenerative spondylolisthesis, or one-level LDH, were identified in the national Swedish spine register (Swespine). We used SF-36 items 11c and 11d to assess future health expectations and present health perceptions. Satisfaction with treatment was assessed using the Swespine satisfaction item. INTERVENTIONS: One-level diskectomy for LDH or one-level decompression for LSS. PRIMARY OUTCOME MEASURES: Satisfaction with treatment. RESULTS: For LSS, the year 1 satisfaction ratio among patients with negative future health expectations preoperatively was 60% (95% CI 58% to 63%), while it was 75% (95% CI 73% to 76%) for patients with positive future health expectations preoperatively. The corresponding numbers for LDH were 73% (95% CI 71% to 75%) and 84% (95% CI 83% to 85%), respectively. CONCLUSIONS: Patients operated for the common lumbar spine diseases LSS or LDH, with negative future general health expectations, were significantly less satisfied with treatment than patients with positive expectations with regard to future general health. These findings are important for patients, and for the surgeons who counsel them, when surgery is a treatment option for LSS or LDH.

Patient-reported Outcome after Surgical Evacuation of Postoperative Spinal Epidural Hematomas at One-year Follow-up.

STUDY DESIGN: Retrospective analysis of prospectively collected data from the National Swedish Spine Register (Swespine). OBJECTIVE: To evaluate the effects of symptomatic spinal epidural hematoma (SSEH) requiring reoperation on one-year patient-reported outcome measures (PROMs) in a large cohort of patients treated surgically for lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Studies exploring the outcomes of reoperations after SSEH are scarce and often lack validated outcome measures. As SSEH is considered a serious complication, understanding of the outcome following hematoma evacuation is important. MATERIALS AND METHODS: After retrieving data from 2007 to 2017 from Swespine, we included all patients with LSS without concomitant spondylolisthesis who were treated surgically with decompression without fusion. Patients with evacuated SSEH were identified in the registry. Back/leg pain numerical rating scales (NRS), the Oswestry Disability Index (ODI), and EQ VAS were used for outcome assessment. PROMs before and one-year after decompression surgery were compared between evacuated patients and all other patients. Multivariate linear regression was performed to determine if hematoma evacuation predicted inferior one-year PROM scores. RESULTS: A total of 113 patients with an evacuated SSEH were compared with 19527 patients with no evacuation. One-year after decompression surgery, both groups showed significant improvement in all PROMs. When comparing the two groups' one-year improvement there were no significant differences in any PROM. The proportion of patients achieving the minimum important change was not significantly different for any PROM. Multivariate linear regression found that hematoma evacuation significantly predicted inferior one-year ODI (ß=4.35, P=0.043), but it was not a significant predictor of inferior NRS Back (ß=0.50, P=0.105), NRS Leg (ß=0.41, P=0.221), or EQ VAS (ß=-1.97, P=0.470). CONCLUSIONS: A surgically evacuated SSEH does not affect outcome in terms of back/leg pain or health-related quality of life. Commonly used PROM surveys may not capture neurologic deficits associated with SSEH.

A Novel Treatment of Pediatric Atlanto-Occipital Dislocation with Nonfusion Using Muscle-Preserving Temporary Internal Fixation of C0-C2: Case Series and Technical Note.

Study Design Case series with surgical technical note. Objectives This article reports experiences and results of muscle-preserving temporary C0-C2 fixation for the treatment of atlanto-occipital dislocation (AOD). Methods AOD is a rare injury caused by high-energy trauma, occurring in less than 1% of pediatric trauma patients. Recommended treatment is C0-C2 fusion which, however, will result in significant loss of mobility in the craniocervical junction (CCJ), especially C1-C2 rotation. An alternative approach, with the ability of preserving mobility in the C1-C2 segment, is a temporary fixation that allows the ligaments to heal, after which the implants can be removed to regain function in the CCJ joints. By using a muscle-preserving approach and navigation for the C2 screws, a relatively atraumatic fixation of the CCJ can be achieved with motion recovery after implant removal. Results We present two cases of AOD treated with temporary fixation. A 12-year-old boy involved in a frontal car collision, as a strapped back seat passenger, was treated with temporary C0-C2 fixation for 10 months. Follow-up at 11 months after implant removal included clinical evaluation, computed tomography, magnetic resonance imaging (MRI), and flexion-extension X-rays. He was free of symptoms at follow-up. The CCJ was radiographically stable and he had 45 degrees of C1-C2 rotation. A 7-year-old girl was hit by a car as she got off a bus. She was treated with temporary fixation for 4 months after which the implant was removed. Follow-up at 8 years included clinical evaluation and MRI in rotation. She was free of symptoms. The ligaments of the CCJ appeared normal and her C1-C2 rotation was 30 degrees. Conclusion C0-C2 fixation without fusion allows the CCJ ligaments to heal in pediatric AOD. By removing the implants after ligament healing, rotation in the C1-C2 segment can be regained without subsequent instability. Both our patients tolerated the treatment well and were free of symptoms at follow-up. By using minimally invasive muscle-preserving technique and navigation, temporary fixation of the CCJ can be achieved with minimal damage to the soft tissues allowing recovery of almost normal function after implant removal.

Handling of missing items in the Oswestry disability index and the neck disability index. A study from Swespine, the National Swedish spine register.

PURPOSE: The Oswestry Disability Index (ODI) and the Neck Disability Index (NDI) scoring algorithms used by the Swedish spine register (Swespine) until April 2022 handled missing items somewhat differently than the original algorithms. The purpose of the current study was to evaluate possible differences in the ODI and NDI scores between the Swespine and the original scoring algorithms. METHODS: Patients surgically treated for degenerative conditions of the lumbar or cervical spine between 2003-2019 (lumbar) and 2006-2019 (cervical) were identified in Swespine. Preoperative and 1-year postoperative ODI/NDI data were used to evaluate differences between the Swespine and the original ODI/NDI algorithms with adjustment for at most 1 or 2 missing items using mean imputation. RESULTS: The preoperative as well as the 1-year postoperative ODI/NDI were approximately 1 unit out of 100 smaller for the Swespine algorithm, irrespective of adjustment model. The differences between preoperative and postoperative ODI/NDI scores were similar between the Swespine and the original scoring algorithms. There were occasional statistically significant differences between the preoperative-postoperative differences due to large sample sizes. CONCLUSIONS: The Swespine algorithms, used until April 2022, underestimated the ODI and NDI by approximately 1 out of 100 units compared with the original algorithms. In addition, there were no statistically significant differences between the original algorithms when adjusting for at most 1 or 2 missing items. The algorithm has now been changed, also for historical data.

The minimal important change for the EQ VAS based on the SF-36 health transition item: observations from 25772 spine surgery procedures.

PURPOSE: The EQ VAS is an integral part of EQ-5D, a commonly used instrument for health-related quality of life assessment. This study aimed to calculate the minimal important change (MIC) thresholds for the EQ VAS for improvement and deterioration after surgery for disk herniation or spinal stenosis. METHODS: Patients, who were surgically treated for disk herniation or spinal stenosis between 2007 and 2016, were recruited from the Swedish spine register. Preoperative and 1-year postoperative data for a total of 25772 procedures were available for analysis. We used two anchor-based methods to estimate MIC for EQ VAS: (1) a predictive model based on logistic regression and (2) receiver operating characteristics (ROC) curves. The SF-36 health transition item was used as anchor. RESULTS: The EQ VAS MIC threshold for improvement after disk herniation surgery ranged from 8.25 to 11.8 while the corresponding value for deterioration ranged from - 6.17 to 0.5. For spinal stenosis surgery the corresponding MIC values ranged from 10.5 to 14.5 and - 7.16 to - 6.5 respectively. There were moderate negative correlations (disk herniation - 0.47, spinal stenosis - 0.46) between the 1 year change in the EQ VAS and the SF-36 health transition item (MIC anchor). CONCLUSIONS: For EQ VAS, we recommend a MIC threshold of 12 points for improvement after surgery for disk herniation or spinal stenosis, whereas the corresponding threshold for deterioration is - 7 points. There are marked differences between the EQ VAS MIC for improvement and deterioration after surgery for disk herniation or spinal stenosis. The MIC value varied depending on the method used for MIC estimation.

Stability of SF-36 profiles between 2007 and 2016: A study of 27,302 patients surgically treated for lumbar spine diseases.

BACKGROUND: Previous studies have shown that patients with different lumbar spine diseases report different SF-36 profiles, but data on the stability of the SF-36 profiles are limited. The primary aim of the current study was to evaluate the stability of the SF-36 profile for lumbar spine diseases. METHODS: Patients, surgically treated between 2007 and 2016 for three lumbar spine diseases, lumbar spinal stenosis (LSS) with degenerative spondylolisthesis (DS), LSS without DS, and lumbar disk herniations (LDH), were identified in the Swedish spine register. Preoperative and 1 year postoperative SF-36 data for a total of 27,302 procedures were available for analysis. The stability of the SF-36 profiles over the 10-year period was evaluated using graphical exploration, linear regression, difference in means, and 95% confidence intervals. The responsiveness of the SF-36 domains to surgical treatment was evaluated using the standardized response mean (SRM). RESULTS: LSS and LDH have different SF-36 profiles. LSS with DS and LSS without DS have similar SF-36 profiles. The preoperative and the 1 year postoperative SF-36 profiles were stable from 2007 to 2016 for all three diagnoses. There were no major changes in the effect size of change (SRM) during the study period for all three diagnoses. For LSS with DS, the number of fusions peaked in 2010 and then decreased. The postoperative SF-36 profiles for LSS with DS were unaffected by changes in surgical treatment trends. CONCLUSIONS: Patients with lumbar spinal stenosis and lumbar disk herniations have different SF-36 profiles. Concomitant degenerative spondylolisthesis had no impact on the SF-36 profile of lumbar spinal stenosis. Adding fusion to the decompression did not alter the postoperative SF-36 profile of lumbar spinal stenosis. The SF-36 health profiles are stable from a 10 years perspective.

Additional operations after surgery for lumbar disc prolapse : indications, type of surgery, and long-term follow-up of primary operations performed from 2007 to 2008.

AIMS: Lumbar disc prolapse is a frequent indication for surgery. The few available long-term follow-up studies focus mainly on repeated surgery for recurrent disease. The aim of this study was to analyze all reasons for additional surgery for patients operated on for a primary lumbar disc prolapse. METHODS: We retrieved data from the Swedish spine register about 3,291 patients who underwent primary surgery for a lumbar disc prolapse between January 2007 and December 2008. These patients were followed until December 2020 to record all additional lumbar spine operations and the reason for them. RESULTS: In total, 681 of the 3,291 patients (21%) needed one or more additional operations. More than three additional operations was uncommon (2%; 15/906). Overall, 906 additional operations were identified during the time period, with a mean time to the first of these of 3.7 years (SD 3.6). The most common reason for an additional operation was recurrent disc prolapse (47%; 426/906), followed by spinal stenosis or degenerative spondylolisthesis (19%; 176/906), and segmental pain (16%; 145/906). The most common surgical procedures were revision discectomy (43%; 385/906) and instrumented fusion (22%; 200/906). Degenerative spinal conditions other than disc prolapse became a more common reason for additional surgery with increasing length of follow-up. Most patients achieved the minimally important change (MIC) for the patient-reported outcomes after the index surgery. After the third additional spinal operation, only 20% (5/25) achieved the MIC in terms of leg pain, and 29% (7/24) in terms of the EuroQol five-dimension index questionnaire visual analogue scale. CONCLUSION: More than one in five patients operated on for a lumbar disc prolapse underwent further surgery during the 13-year follow-up period. Recurrent disc prolapse was the most common reason for additional surgery, followed by spinal stenosis and segmental pain. This study shows that additional operations after primary disc surgery are needed more frequently than previously reported, and that the outcome profoundly deteriorates after the second additional operation. The findings from this study can be used in the shared decision-making process. Cite this article: Bone Joint J 2022;104-B(5):627-632.

Additional operation rates after surgery for degenerative spine diseases: minimum 10 years follow-up of 4705 patients in the national Swedish spine register.

OBJECTIVES: To identify rates of additional operation after the index operation for degenerative lumbar spine diseases. DESIGN: Retrospective register study. SETTING: National outcome data from Swespine, the National Swedish spine register. PARTICIPANTS: A total of 4705 patients who underwent one-level surgery for degenerative disk disease (DDD) or lumbar spinal stenosis (LSS) with or without degenerative spondylolisthesis (DS) between 1 January 2007 and 31 December 2010 were followed from 1 January 2007 to 31 December 2020 to record all cases of additional lumbar spine operations. INTERVENTIONS: One-level spinal decompression and/or posterolateral fusion for degenerative spine diseases. PRIMARY OUTCOME MEASURES: Number of additional operations. RESULTS: Additional operations were more common at adjacent levels for patients with LSS with DS treated with decompression and fusion whereas additional operations were more evenly distributed between the index level and the adjacent levels for DDD treated with fusion and LSS with and without DS treated with decompression only. For patients younger than 60 years, treated with decompression and fusion for LSS with DS, the additional operations were evenly distributed between the index level and the adjacent levels. CONCLUSIONS: There are different patterns of additional operations following the index procedure after surgery for degenerative spine diseases. Rigidity across previously mobile segments is not the only important factor in the development of adjacent segment disease (ASD) after spinal fusion, also the underlying disease and age may play parts in ASD development. The findings of this study can be used in the shared decision-making process when surgery is a treatment option for patients with degenerative lumbar spine diseases as the first operation may be the start of a series of additional spinal operations for other degenerative spinal conditions, either at the index level or at other spinal levels.

Reoperations After Decompression With or Without Fusion for L3-4 Spinal Stenosis With Degenerative Spondylolisthesis: A Study of 372 Patients in Swespine, the National Swedish Spine Register.

STUDY DESIGN: Register study with prospectively collected data. OBJECTIVE: The aim was to investigate reoperation rates at the index level and the adjacent levels after surgery for lumbar L3-4 spinal stenosis with concomitant degenerative spondylolisthesis (DS). SUMMARY OF BACKGROUND DATA: There are different opinions on how to surgically address lumbar spinal stenosis with DS. The potential benefit of fusion surgery should be weighed against the risks of future reoperations because of adjacent segment degeneration. Data on the reoperation rate at adjacent segments after single level L3-4 fusion surgery are limited. MATERIALS AND METHODS: A total of 372 patients, who underwent surgery for lumbar L3-4 spinal stenosis with DS (slip >3 mm) between 2007 and 2012, were followed between 2007 and 2017 to identify reoperations at the index level and adjacent levels. The reoperation rate for decompression and fusion was compared with the reoperation rate for decompression only. Patient-reported outcome measures before and 1 year after surgery were evaluated. RESULTS: The reoperation rate at the index level (L3-4) was 3.5% for decompression and fusion and 5.6% for decompression only. At the cranial adjacent level (L2-3), the corresponding numbers were 6.6% and 4.2%, respectively, and the caudal adjacent level (L4-5), the corresponding numbers were 3.1% and 4.9%, respectively. The effect sizes of change were larger for decompression and fusion compared with decompression only. The effect sizes of change were similar for leg pain and back pain. CONCLUSIONS: We could not identify any differences in reoperation rates at the cranial or caudal adjacent segment after decompression and fusion compared with decompression only for L3-4 spinal stenosis with DS. The improvement in back pain is similar to the improvement in leg pain after surgery for L3-4 spinal stenosis with DS.

Patients with no preoperative back pain have the best outcome after lumbar disc herniation surgery.

PURPOSE: Most patients with lumbar disc herniations requiring surgery have concomitant back pain. The purpose of the current study was to evaluate the outcome of surgery for lumbar disc herniations in patients with no preoperative back pain (NBP) compared to those reporting low back pain (LBP). METHODS: 15,418 patients surgically treated due to LDH with primary discectomy from 1998 until 2020 were included in the study. Self-reported low back pain assessed with a numerical rating scale (NRS) was used to dichotomize the patients in two groups, patients without preoperative back pain (NBP, NRS = 0, n = 1333, 9%) and patients with preoperative low back pain (LBP, NRS > 0, n = 14,085, 91%). Patient reported outcome measures (PROMs) collected preoperatively and one-year postoperatively were used to evaluate differences in outcomes between the groups. RESULTS: At the one-year follow-up, 89% of the patients in the NBP group were completely pain free or much better compared with 76% in the LBP group. Significant improvement regarding leg pain was seen in all measured PROMs in both groups oneyear after surgery. In the NBP group, 13% reported clinically significant back pain (NRS difference greater than Minimally Clinical Important Difference (MICD)) at the one-year follow-up. CONCLUSIONS: Patients without preoperative back pain are good candidates for LDH surgery. 13% of patients without preoperative back pain develop clinically significant back pain one-year after surgery.

Responsiveness of the SF-36 general health domain: observations from 14883 spine surgery procedures.

PURPOSE: The study evaluated perceptions of general health (GH) after surgical treatment of spinal stenosis and disk herniation. We used a large longitudinally collected data set to explore differences in responsiveness between the SF-36 GH domain, EQ VAS, EQ-5D index, and SF-6D index. METHODS: Patients, surgically treated for lumbar spinal stenosis or lumbar disk herniation between 2007 and 2017, were recruited from the national Swedish spine register. A total of 14,883 procedures were eligible for analysis. The responsiveness of the SF-36 GH domain to surgical treatment was evaluated with the standardized response mean (SRM) and effect size (ES). The internal consistency of the GH domain was evaluated, ceiling and floor effects were assessed, and the correlation between GH domain and EQ VAS was analyzed. RESULTS: The SF-36 GH domain did not respond to surgical treatment of spinal stenosis and disk herniation. In contrast, EQ VAS, EQ-5D index, and SF-6D showed moderate to large responsiveness. There were pronounced ceiling effects in items 11a-c of the SF-36 GH domain. There was a negative effect size of change for item 11c. The internal consistency of the GH domain was satisfactory. There were marked differences in the correlations between EQ VAS and the GH domain preoperatively and postoperatively. CONCLUSIONS: The SF-36 GH domain should be used with caution when evaluating effects on GH perceptions after spine surgery procedures. The lack of responsiveness is most probably explained by ceiling effects for items 11a-c and a negative effect size of change for item 11c.

Single item self-rated general health: SF-36 based observations from 16,910 spine surgery procedures.

PURPOSE: In spine surgery single item patient-reported outcome assessment has been used for many years. Items 1 and 2 of SF-36 are used for assessment of general health. We used these items to explore single item, self-rated, general health assessment after spine surgery. METHODS: Patients operated for lumbar disc herniation or lumbar spinal stenosis between 2007 and 2017, were recruited from the national Swedish spine register. A total of 16,910 procedures were eligible for analysis. The responsiveness of the SF-36 general health assessment items to surgical treatment was evaluated with the standardized response mean (SRM). Improvement in self-rated general health was used to dichotomize SF-36 profiles and EQ VAS distributions. RESULTS: For disc herniation, 5852 (83%) patients reported improvement in general health 1 year after surgery. For spinal stenosis, the corresponding numbers were 6,482 (66%). The additional improvement after year 1 was small. The responsiveness of the SF-36 item 2 (the health transition item) to surgical treatment of disc herniation or spinal stenosis was substantial. There was a clear association between improvement in SF-36 item 2 and improvements in all domains of SF-36. CONCLUSIONS: Surgery for disc herniation or spinal stenosis improve patients' perception of general health 1 year after surgery. The improvement in general health after year 1 is limited. The SF-36 item 2 is a responsive measure of self-rated general health that may be used for dichotomization of SF-36 and EQ VAS data when evaluating surgical outcome in spine surgery.

Properties of the EQ-5D-5L when prospective longitudinal data from 28,902 total hip arthroplasty procedures are applied to different European EQ-5D-5L value sets.

BACKGROUND: The purpose of this study was to evaluate the impact of using different country-specific value sets in EQ-5D-5L based outcome analyses. METHODS: We obtained data on patients surgically treated with total hip arthroplasty (THA) between 2017 and 2019 from the national Swedish Hip Arthroplasty Register. Preoperative and one-year postoperative data on a total of 28,902 procedures were available for analysis. The EQ-5D-5L health states were coded to the EQ-5D-5L preference indices using 13 European value sets. The EQ-5D-5L index distributions were then estimated with kernel density estimation. The change in EQ-5D-5L index before and one year after treatment was evaluated with the standardized response mean (SRM). The lifetime gain in quality-adjusted life years (QALYs) was estimated with a 3.5% annual QALY discount rate. FINDINGS: There was a marked variability in means and shapes of the resulting EQ-5D-5L index distributions. There were also considerable differences in the EQ-5D-5L index distribution shape before and after the treatment using the same value set. The effect sizes of one-year change (SRM) were similar for all value sets. However, the differences in estimated QALY gains were substantial. INTERPRETATION: The EQ-5D-5L index distributions varied considerably when a single large data set was applied to different European EQ-5D-5L value sets. The most pronounced differences were between the value sets based on experience-based valuation and the value sets based on hypothetical valuation. This illustrates that experience-based and hypothetical value sets are inherently different and also that QALY gains derived with different value sets are not comparable. Our findings are of importance in study planning since the results and conclusions of a study depend on the choice of value set. FUNDING: None.

Properties of SF-6D when longitudinal data from 16,398 spine surgery procedures is applied to 9 national SF-6D value sets.

Background and purpose - There are several national value sets for SF-6D. For studies conducted in countries without a country-specific value set the authors may use a value set from a neighboring or culturally similar county. We evaluated the consequences of using different national value sets in SF-6D index-based outcome analyses.Patients and methods - Patients surgically treated for lumbar spinal stenosis or lumbar disk herniation between 2007 and 2017 were recruited from the national Swedish spine register. 16,398 procedures were eligible for analysis. The SF-6D health states were coded to SF-6D preference indices using value sets for 9 countries. The SF-6D index distributions were then estimated with kernel density estimation. The change in SF-6D index before and after treatment was evaluated with the standardized response mean (SRM).Results - There was a marked variability in mean and shape for the resulting SF-6D index distributions. There were considerable differences in SF-6D index distribution shape before and after treatment using the same value set. The effect sizes of 2-year change (SRM) were in most cases similar when the 9 value sets were applied on pre- and post-treatment data.Interpretation - We found a marked variability in SF-6D index distributions when a single large data set was applied to 9 national SF-6D value sets. Consequently, we recommend that SF-6D index data from studies conducted in countries without country-specific SF-6D value sets is interpreted with caution.

Properties of the EQ-5D-3L index distribution when longitudinal data from 27,328 spine surgery procedures are applied to nine national EQ-5D-3L value sets.

PURPOSE: The purpose of the current study was to apply a single large longitudinal EQ-5D-3L data set to several national EQ-5D-3L value sets and explore differences in EQ-5D-3L index density functions and effect sizes before and after treatment. METHODS: Patients, surgically treated for lumbar spinal stenosis or lumbar disk herniation between 2007 and 2017, were recruited from the national Swedish spine register. A total of 27,328 procedures were eligible for analysis. The EQ-5D health states were coded to EQ-5D-3L summary indices using value sets for 9 countries: Argentina, Australia, Canada, China, Germany, Italy, Sweden, the UK, and the US. The EQ-5D-3L summary index distributions were then estimated with kernel density estimation. The change in EQ-5D-3L index before and after treatment was evaluated with the standardized response mean (SRM). RESULTS: There was a high variability in the resulting EQ-5D-3L index density functions. There were also considerable differences in EQ-5D-3L index density functions before and after treatment using the same value set. Effect sizes of 2-year change (SRM), however, were similar when the 9 value sets were applied on pre- and post-treatment data. CONCLUSIONS: We found a marked variability in EQ-5D-3L index density functions when a single large data set was applied to 9 national EQ-5D-3L value sets. Consequently, studies that aggregate international data, e.g. meta-analyses, may produce misleading results if the underlying differences in EQ-5D-3L index density functions are inadequately handled. On the basis of the results of our study, we recommend against pooling of different national EQ-5D-3L index data.

Reoperations after decompression with or without fusion for L4-5 spinal stenosis with or without degenerative spondylolisthesis: a study of 6,532 patients in Swespine, the national Swedish spine register.

Background and purpose - There are different opinions on how to surgically address lumbar spinal stenosis with concomitant degenerative spondylolisthesis (DS). We investigated reoperation rates at the index and adjacent levels after L4-5 fusion surgery in a large cohort of unselected patients registered in Swespine, the national Swedish spine register.Patients and methods - 6,532 patients, who underwent surgery for L4-5 spinal stenosis with or without DS between 2007 and 2012, were followed up to 2017 to identify reoperations at the index and adjacent levels. The reoperation rates for decompression and fusion were compared with the reoperation rates for decompression only and for patients with or without DS. Patient-reported outcome data were collected preoperatively, and at 1 and 2 years after surgery and used to evaluate differences in outcome between index operations and reoperations.Results - For spinal stenosis with DS, the reoperation rate at the index level was 3.0% for decompression and fusion and 6.0% for decompression only. At the adjacent level, the corresponding numbers were 9.7% and 4.2% respectively. For spinal stenosis without DS, the reoperation rate at the index level was 3.7% for decompression and fusion and 6.2% after decompression only. At the adjacent level, the corresponding numbers were 8.1% and 3.8% respectively. For the reoperations at the adjacent level, there was no difference in patient-reported outcome between extended fusion or decompression only.Interpretation - Single-level lumbar fusion surgery is associated with an increased rate of reoperations at the adjacent level compared with decompression only. When reoperations at the index level are included there is no difference in reoperation rates between fusion and decompression only.

Clinical appearance and reliability in visual assessment after in situ fusion for high-grade isthmic spondylolisthesis.

PURPOSE: The current literature on clinical appearance after surgery for high-grade spondylolisthesis is inconclusive. The few long-term comparative studies on surgical reduction versus in situ fusion report contradictory findings concerning appearance-related issues. The purpose of the current study was to evaluate and quantify clinical appearance three decades after in situ fusion for high-grade isthmic spondylolisthesis. METHODS: The Scoliosis Research Society (SRS)-22r questionnaire, digital photographs and standing lateral radiographs were used to evaluate clinical appearance for 22 patients three decades after in situ fusion for high-grade spondylolisthesis. The appearance was assessed by two spine surgeons, by the patient themselves, and by quantification of cosmesis relevant radiographic variables including pelvic parameters and sagittal balance. RESULTS: The surgeon inter- and intraobserver reliability of the photographic evaluation of the trunk deformity was at most moderate (Cohen's kappa 0.5). Correlation analysis revealed at most medium correlation between radiographic outcome and self-rated (SRS-22r) self-image (Spearman's rank correlation coefficient 0.3). The agreement between patient and surgeon-rated trunk appearance was poor (Cohen's kappa 0.2). CONCLUSIONS: Photographic evaluation of the trunk deformity in high-grade spondylolisthesis is unreliable. There were only weak correlations between patient self-assessed trunk appearance and radiographic parameters. The results reflect the pronounced subjectivity of cosmesis, and that the trunk deformity in high-grade spondylolisthesis is not easily observed. LEVEL OF EVIDENCE: IV.

Adjacent segment disk degeneration three decades after fusion without attempted reduction for high-grade isthmic spondylolisthesis.

STUDY DESIGN: Observational study. OBJECTIVES: To evaluate adjacent segment disk degeneration (ASD) after fusion without attempted reduction at a young age for high-grade isthmic spondylolisthesis. The clinical relevance of ASD remains unclear. Previous studies have shown that spinal fusion is associated with increased ASD but without influence on clinical outcome. Since high-grade spondylolisthesis is a severe kyphotic deformity, one could hypothesize that fusion without attempted reduction in young patients leads to accelerated adjacent segment disk degeneration in adult life. METHODS: Anterior and posterior disk heights were evaluated on supine radiographs of the spine 8 years and 29 years after fusion without attempted reduction for high-grade spondylolisthesis and also on standing radiographs 8 years and 33 years after surgery. Pelvic parameters were evaluated on standing radiographs obtained 33 years after surgery. Health-related quality of life was evaluated with the Scoliosis Research Society (SRS)-22r questionnaire. RESULTS: One segment above fusion the anterior disk height significantly decreased on standing radiographs. Two segments above the fusion, the anterior disk height significantly decreased on supine as well as on standing radiographs. The largest reduction was found two segments above the fusion where the disk height was reduced from 33 to 28% of anterior vertebral height between the measurements at mean 8 years and mean 33 years after surgery. There were no statistically significant decreases in posterior disk heights in any measurement. The disk height showed a moderate negative correlation to PT. There was no correlation between disk height reduction and SRS-22r outcome. CONCLUSIONS: In our long-term follow-up of fusion without attempted reduction for high-grade spondylolisthesis in young patients, we found only a minor but statistically significant reduction in adjacent segment disk height which had no apparent impact on clinical outcome. LEVEL OF EVIDENCE: Level IV.