Validity of a single-item measure to assess leg or back pain as the predominant symptom in patients with degenerative disorders of the lumbar spine

Problem resolution scale: A single-item instrument for easily assessing clinical improvement

This study describes the development and tests the validity of the Problem Resolution Scale (PRS)-a single-item measure developed by researchers at Systemic Practice Research Network (SYPRENE) for assessing the degree to which the focal problem of therapy is perceived as resolved. Data were collected at termination from 747 clients seen across 18 therapists. Results suggested good construct validity, supported by a strong correlation between client and therapist perceptions as assessed by the PRS (r = 0.71, p < 0.001). Good criterion validity was also supported by strong correlations between client-reported psychological well-being and functioning at termination and both client-reported (r = -0.63; p < 0.001) and therapist-reported (r = -0.66; p < 0.001) problem resolution scores. Linear mixed model regression and stratified correlation analysis controlling for the therapist and presenting problem effects confirmed criterion validity. Results provide initial evidence for the validity and utility of the PRS.

Is new tech a pain in the neck? The impact of introducing new technologies in home-care on neck pain: a prospective study

BACKGROUND

Home healthcare services are increasingly utilizing novel technologies to enhance quality and efficiency of caregiving, to reduce workloads and compensate for expected labor shortages in the future due to ageing populations. However, rapid, ongoing implementation of new technologies may demand considerable adaptation for employees. The objective of this study was to prospectively examine associations of newly introduced work technologies with neck pain complaints.

METHODS

With a nationally representative prospective sample of home-care workers in Norway (N = 887), we estimated effects of 1) introducing new technologies and 2) the appraised quality of training during implementation on neck pain eight months after.

RESULTS

A majority of employees reported new technologies having been introduced the previous 12 months (73.8%). This was not by itself associated with neck pain. However, perceived high quality of training was associated with less subsequent neck pain, also after adjustment for job demands and job control. The strongest effect was seen for "very good" versus "very poor" quality training (OR 0.35, 95% CI 0.17,0.71, in the fully adjusted model). Cross-lagged path analyses ruled out potential reverse causation stemming from the influence of pain on needs for or appraisals of training.

CONCLUSION

The present findings suggest the introduction of new work technologies has a significant impact on home-care workers' health, depending on the quality of training during implementation. This highlights the need to include training programs in risk assessments when implementing new technologies.

Intraindividual change in pain tolerance and negative affect over 20 years: findings from the MIDUS study

Pain tolerance, defined as the ability to withstand physical pain states, is a clinically important psychobiological process associated with several deleterious outcomes, including increased pain experience, mental health problems, physical health problems, and substance use. A significant body of experimental work indicates that negative affect is associated with pain tolerance, such that increased negative affect is associated with decreased pain tolerance. Although research has documented the associations between pain tolerance and negative affect, little work has examined these associations over time, and how change in pain tolerance is related to changes in negative affect. Therefore, the current study examined the relationship between intraindividual change in self-reported pain tolerance and intraindividual change in negative affect over 20 years in a large, longitudinal, observation-based national sample of adults (n = 4,665, Mage = 46.78, SD =12.50, 53.8% female). Results from parallel process latent growth curve models indicated that slope of pain tolerance and negative affect were associated with each other over time (r = .272, 95% CI [.08, .46] p = .006). Cohen's d effect size estimates provide initial, correlational evidence that changes in pain tolerance may precede changes in negative affect. Given the relevance of pain tolerance to deleterious health outcomes, better understanding how individual difference factors, including negative affect, influence pain tolerance over time, are clinically important to reduce disease-related burden.

Referred pain: characteristics, possible mechanisms, and clinical management

Purpose of this review

Referred pain is a common but less understood symptom that originates from somatic tissues. A comprehensive recognition of referred pain is important for clinicians when dealing with it. The purpose of this study is to summarize the current understanding of referred pain, including its pathogenesis, characteristics, diagnosis, and treatment.

Recent findings

Referred pain arises not only from pathologies primarily involving local tissue but also from lesions in distant structures. Central sensitization of convergent neurons and peripheral reflexes of dichotomizing afferent fibers are two theories proposed to explain the pathological mechanism of referred pain. Because syndromes related to referred pain of different origins overlap each other, it is challenging to define referred pain and identify its originating lesions. Although various approaches have been used in the diagnosis and treatment of referred pain, including conservative treatment, blockade, radiofrequency, and surgery, management of referred pain remains a clinical challenge.

Summary

Unlike radicular pain and neuropathic pain, referred pain is a less studied area, despite being common in clinics. Referred pain can derive from various spinal structures, and blockage helps identify the primary pathology. Due to the heterogeneity of referred pain, treatment outcomes remain uncertain. Further studies are needed to improve our understanding of referred pain.

Development of a Patient-Reported Symptom Item Bank for Patients with Hepatobiliary or Pancreatic Malignancies: A Systematic Review

BACKGROUND

Patients with hepatobiliary or pancreatic cancers often experience severe symptoms, resulting in a sharp decline in functioning, poor quality of life, and increased mortality risk. Early and effective management of symptoms allows a better quality of life and reduced mortality, depending on the selection of appropriate assessment of specific symptoms for a defined purpose. We aimed to develop a symptom measurement item bank for hepatobiliary or pancreatic cancers.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was applied to organize this systematic review. The articles validated patient-reported outcome measures (PROMs) for hepatobiliary or pancreatic cancer and published before December 2021 were retrieved from the Web of Science, PubMed, Embase databases and Cochrane Library. Items from the existing PROMs were selected and classified into different patient-reported symptoms based on the concepts and specific underlying constructs of the objects measured.

RESULTS

Sixteen unique PROMs were identified across the 29 eligible studies included in our analysis. Items from the literature review (14 PROMs with 421 items for which information was obtained) were selected and classified. As a result of this study, we developed a symptom item bank with 40 patient-reported symptoms and 229 assessment items for hepatobiliary or pancreatic cancer, and fatigue, pain and nausea were the most common symptom items.

CONCLUSION

We developed an item bank to assess the patient-reported symptoms of hepatobiliary or pancreatic cancer. This item bank could allow researchers to select appropriate measures of symptom and provide a basis for the development of a single-item symptom-measurement system.

Back Dominant Pain Has Equal Outcomes to Radicular Dominant Pain Following Posterior Lumbar Fusion in Adult Isthmic Spondylolisthesis: A CSORN Study

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

This study aimed to determine how the surgeon-determined and patient-rated location of predominant pain influences patient-rated outcomes at 1-year after posterior lumbar fusion in adult isthmic spondylolisthesis.

METHODS

We retrospectively reviewed consecutive patients prospectively enrolled in the Canadian Spine Outcomes and Research Network national registry between 2009 and 2017 that underwent posterior lumbar fusion for isthmic spondylolisthesis. Using longitudinal mixed-model repeated-measures analysis the change from baseline in patient-reported outcome measures (PROMs) at 1 year after surgery was compared between surgeon-determined groups (back vs. radicular) and between patient-rated pain groups (back, leg, and equal) derived from preoperative pain scores on the numerical rating scale (NRS).

RESULTS

83/252 (33%) patients had a surgeon-determined chief complaint of back pain, while 103 (41%) patients rated their back pain as the predominant pain location, and 78 (31%) rated their back and leg pain to be equal. At baseline patients in the surgeon-determined radicular group had worse NRS-leg pain than those in the back-pain group but equal NRS-back pain. At baseline patients in the patient-rated equal pain group had similar back pain compared to the patient-rated back pain group and similar leg pain compared to the patient-rated leg pain group. All PROMs improved post-operatively and were not different between the 2 groups at 1 year.

CONCLUSIONS

Our study found no difference in outcome, irrespective of whether a surgeon determines the patient's primary pain complaint back or radicular dominant, or the patient rates pain in one location greater than another.

Does the Predominant Pain Location Influence Functional Outcomes, Satisfaction, and Return to Work After Minimally Invasive Transforaminal Lumbar Interbody Fusion For Degenerative Spondylolisthesis?

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

The objective of this study was to determine how different combinations of preoperative back pain (BP) and leg pain (LP) may influence functional outcomes, patient satisfaction and return to work (RTW) in patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Surgical decision-making is often based on the traditional assumption that the predominance of lower extremity symptoms is a stronger indication for lumbar spine surgery. Surprisingly, there is a paucity of literature supporting this notion and the isolated impact of the preoperative pattern of pain on outcome remains unclear.

METHODS

Prospectively collected data for patients who underwent primary MIS-TLIF for degenerative spondylolisthesis were reviewed. Patients were categorized into 3 groups depending on predominant pain location: LP predominant (LP>BP), back pain predominant [(BPP); BP>LP] and equal pain predominance (BP=LP). Patients were prospectively followed for at least 2 years.

RESULTS

In total, 781 patients were included: 33.4% LP predominant, 28.7% BPP and 37.9% equal pain predominance cases. The BPP group was significantly younger (P=0.005) and showed a trend towards poorer baseline Short-Form-36 Mental Component Summary (P=0.069). After adjusting for baseline differences, there was no significant difference in BP, LP, Oswestry Disability Index (ODI), SF-36 Physical Component Summary, and SF-36 Mental Component Summary between the 3 groups at all time points (P>0.05) except for poorer 1-month ODI in the BPP group (P=0.010). The rate of minimal clinically important difference attainment for ODI and SF-36 Physical Component Summary, satisfaction, expectation fulfilment and RTW were also similar (P>0.05).

CONCLUSIONS

The functional outcomes, quality of life and satisfaction after MIS-TLIF were similar, regardless of the predominant pain location. Equal proportions of patients achieved the minimal clinically important difference and RTW. In the context of proper indications, these results suggest that MIS-TLIF can be equally effective for patients with varying combinations of BP or LP.

LEVEL OF EVIDENCE

Level III-nonrandomized cohort study.

Relief of Low Back Pain After Posterior Decompression for Lumbar Spinal Stenosis

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to confirm that decompression for lumbar spinal stenosis (LSS) relieves low back pain (LBP) as adequately as it relieves leg pain and to identify predictors for inadequate LBP relief.

SUMMARY OF BACKGROUND DATA

Although decompression for LSS is generally thought to yield worse results for LBP than for leg pain, some studies have reported similar improvements in pain scores between LBP and leg pain. To treat LBP or take measures to prevent inadequate LBP relief, reliable predictors for LBP relief should be identified.

METHODS

We retrospectively reviewed 175 patients who underwent posterior element-preserving decompression and evaluated the relief of LBP and leg pain using numeric rating scales (NRSs). Associations between demographic, clinical, or imaging parameters and LBP relief at 1 and 4 years were analyzed by stepwise linear regression analyses. The imaging parameters included Modic change type 1, disc degeneration, foraminal stenosis, vertebral slipping (within Grade 1), scoliosis (<15°) and lordosis.

RESULTS

The mean improvements in LBP and leg pain NRS scores from baseline were 5.22 and 4.70 points (P = 0.064, paired t test) at 1 year and 5.12 and 4.62 points (P = 0.068) at 4 years, respectively. Poor LBP scores at 4 years were significantly associated with long-lasting LBP (beta = 0.31, P < 0.0001) and moderate or severe arm symptoms with cervical spinal cord compression or intramedullary hyperintense signal on T2-weighted MRI (beta = 0.22, P = 0.0014). The imaging parameters of the lumbar spine failed to show clear associations with poor LBP scores at 4 years, although Modic change type 1 showed a significant association with poor LBP scores at 1 year (beta = 0.28, P < 0.0001).

CONCLUSION

Posterior decompression relieves LBP as well as leg pain. Long-lasting LBP and concurrent symptomatic cervical myelopathy are important predictors for inadequate LBP relief. There were no reliable imaging parameters predictive of inadequate LBP relief.Level of Evidence: 4.

Leadership Style, Headache, and Neck Pain: The Moderating Role of the Catechol-O-Methyltransferase (COMT) Genotype

OBJECTIVE

Leadership styles can influence subordinates' health. We investigated how the gene encoding the Catechol-O-Methyltransferase (COMT) enzyme (ie, COMT rs4680 Val158Met) influenced effects of abusive supervision and transformational leadership on subordinates' headache and neck pain.

METHODS

Multiple group structural equation modeling (SEM) was employed to test associations of leadership with subordinates' pain 6 months after in a representative sample of the Norwegian working population (n = 996). Genotyping was performed by TaqMan technology.

RESULTS

Abusive supervision was associated with increased risk, and transformational leadership with decreased risk, of headache and neck pain. Both leadership styles exhibited more pronounced effects in individuals with the Met/Met genotype.

CONCLUSION

Met/Met employees were relatively vulnerable to adversity, but also relatively responsive to constructive leadership. Many workers may benefit more from constructive leadership than population-averaged associations might suggest.

Patients with predominantly back pain at the time of lumbar fusion for low-grade spondylolisthesis experience similar clinical improvement to patients with predominantly leg pain: mid-term results

BACKGROUND CONTEXT

Patients with back pain predominance (BPP) have traditionally been thought to derive less predictable symptomatic relief from lumbar fusion surgery.

PURPOSE

To compare postoperative clinical outcomes as well as degree of improvement in clinical outcome measures between patients with BPP and patients with leg pain predominance (LPP) undergoing open posterior lumbar fusion.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Analysis of patients who underwent an open posterior lumbar fusion for low-grade (Meyerding Grade I or II) degenerative or isthmic spondylolisthesis from 2011 to 2018 was conducted. Surgery was indicated after failure of conservative treatment to address radiculopathy and/or neurogenic claudication. Patients were excluded if they were under 18 years of age at the time of surgery, had less than 6 months of follow-up, presented with a lumbar vertebral body fracture, tumor, or infection, or underwent a fusion surgery that extended to the thoracic spine, high-grade spondylolisthesis, or concomitant deformity.

OUTCOME MEASURES

Radiographs obtained at preoperative, immediate postoperative, and final visits were evaluated for presence or absence of fusion. Patient-reported outcomes were recorded at preoperative and final clinic visits that included: visual analog scale (VAS) back/leg pain, and Oswestry disability index (ODI). Achievement of minimal clinically important difference (MCID) was analyzed, along with rates of postoperative complication and reoperation.

METHODS

Preoperative and final patient-reported outcomes were obtained. Achievement of MCID was evaluated using following thresholds: ODI 14.9, VAS-back pain 2.1, VAS-leg pain 2.8. For analysis, patients were divided into two groups based on predominant location of pain: predominantly VAS-back pain (BPP) and predominantly VAS-leg pain (LPP).

RESULTS

One hundred forty-one patients met inclusion criteria. Of these, 71 had LPP, and 70 had BPP. Patients with preoperative LPP experienced greater improvements in VAS-leg (p<.001) compared to those with BPP, whereas patients with preoperative BPP experienced greater improvements in VAS-back (p=.011) postoperatively compared to those with LPP. There were no differences in the final clinical outcomes. Additionally, LPP achieved MCID for VAS-leg (p=.027) at significantly higher proportion than BPP and BPP achieved MCID for VAS-back (p=.050) at significantly higher proportion than LPP.

CONCLUSIONS

Patients with low-grade spondylolisthesis who underwent an open posterior lumbar fusion had improvement in symptoms regardless of presentation with BPP or LPP. In properly indicated patients, posterior spinal fusion is effective for those with BPP in the setting of experiencing both leg and back pain, and clinicians can use this information for perioperative discussions and surgical decision-making.

Human resource primacy, dispositional optimism, and chest pain: A prospective, cross-lagged study of work, personality, and health

Chest pain (CP) is common, frightening, and often medically unexplained. Occupational psychological factors are associated with somatic pain. Personality may influence both perceived working conditions and somatic health, thereby confounding associations of work with health. Despite this, very few studies have investigated the interplay between work factors, personality and pain. The current study assessed relationships of a relatively novel work factor, human resource primacy (HRP), and a personality factor known to be relevant to health, dispositional optimism (Opt), with CP across two years (N = 6714). A series of structural equation models (SEMs) were fitted, modeling "substantive" and "confounded" relationships of psychological factors with CP. A "common latent factor" (CLF) was included to account for bias by unmeasured factors that may have influenced all variables (e.g. reporting bias) and the role of optimism as a possible confounder of the relationship between HRP and CP was investigated specifically. Independent effects of HRP and Opt on CP were observed. No effects of HRP/CP on Opt were observed. Opt appeared to confound the relationship between HRP and CP to some extent. However, best fit was observed for a "reciprocal" model with independent lagged effects from HRP/Opt to CP as well as from CP/Opt to HRP. Thus, results suggested a mutual causal dynamic between HRP and CP along with an influence of Opt on both HRP and CP-implying that working conditions influence the experience of chest pain while the chest pain also influences the experience of working conditions. Optimistic dispositions may influence the experience of both work and pain, but not to an extent that fully explains their relationship. Hence, the notion that associations of HRP with CP are mere artifacts of optimistic/pessimistic reporting was not supported. More likely, complex reciprocal relationships exist between these factors, in which mutual reinforcements occur and both vicious and virtuous cycles may result.

Development of the Japanese Core Outcome Measures Index (COMI): cross-cultural adaptation and psychometric validation

Background

The patient-rated Core Outcome Measures Index (COMI) assesses the multidimensional impact of back problems on the sufferer. The brevity and comprehensibility of the tool make it practical for use in clinical and research settings. Although the COMI has been cross-culturally adapted in various languages worldwide, there is currently no Japanese version. The aim of this study was to develop a Japanese version of the COMI by: (1) performing a cross-cultural adaptation of the English version and (2) evaluating the psychometric properties of the Japanese version of the COMI in Japanese volunteers with chronic back problems.

Methods

The English version of the COMI was cross-culturally adapted for the Japanese language using established guidelines. The pre-final version was pilot-tested in five Japanese-speaking patients with low back pain (LBP) and a history of spine surgery. The psychometric properties of the Japanese COMI were tested in a group of 1052 individuals with chronic LBP (LBP ≥3 months), aged 20–69 years, who were recruited through a web-based survey. The psychometric properties that were evaluated included convergent and known-group validity, using the following reference questionnaires: EuroQol 5 Dimension, Roland Morris Disability Questionnaire, Short Form 8™ Health Survey, and the Keele STarT Back Screening Tool.

Results

The pre-final version of the cross-culturally adapted Japanese COMI was completed without any major problems of understanding or acceptability. For the evaluation of its psychometric properties, tests for convergent validity showed moderate correlations between COMI items and the respective reference questionnaires for symptom-specific well-being [− 0.33–−0.48] and disability domains [0.48] and strong correlations (> 0.5) for the other domains and the COMI summary score. The analysis of known-group validity showed a linear trend for the COMI score in relation to prognostic risk (P < 0.001).

Conclusions

The Japanese COMI retained conceptual equivalence to the original using comprehensible and acceptable Japanese expressions. We developed a Japanese version of the COMI that displayed qualities that support its convergent and known-group validity. The availability of a Japanese version of the COMI should allow for improved documentation of the care provided to patients with back problems.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-1986-x) contains supplementary material, which is available to authorized users.

Prevalence and Location of Neuropathic Pain in Lumbar Spinal Disorders: Analysis of 1804 Consecutive Patients With Primary Lower Back Pain

STUDY DESIGN

A cross-sectional study of 1804 consecutive patients.

OBJECTIVE

The aim of this study was to investigate the prevalence of pathological pain and its distribution features in patients with chronic lumbar spinal disorders.

SUMMARY OF BACKGROUND DATA

Clinical spinal disorders can involve pathological neuropathic pain (NeP) as well as physiological nociceptive pain (NocP), as they have varied pathology, including spinal cord injury, stenosis, and compression. A study conducted by the Japanese Society for Spine Surgery and Related Research (JSSR) has determined a prevalence of 29.4% for NeP in patients with lumbar spinal disorder. However, the data did not include information on pain location.

METHODS

Patients aged 20 to 79 years with chronic lower back pain (≥3 months, visual analog scale score ≥30) were recruited from 137 JSSR-related institutions. Patient data included an NeP screening questionnaire score and pain location (lower back, buttock, and legs). The association between the pain pathology and its location was analyzed statistically using the unpaired t test and Chi-square test followed by Fisher test. P < 0.05 was considered significant.

RESULTS

Low back pain subjects showed 31.9% of NeP prevalence, and the pain distribution showed [NocP(%)/NeP(%)] low back pain only cases: 44/22, while low back pain with leg pain cases showed a prevalence of 56/78. This indicates that low back pain alone can significantly induce NocP rather than NeP (P < 0.01). Buttock pain was revealed to significantly induce both lower back pain and leg pain with NeP properties (P < 0.01). Leg pain was revealed to be predominantly neuropathic, especially when it included peripheral pain (P < 0.01).

CONCLUSION

Low back pain with no buttock pain induces NocP rather than NeP. Buttock pain is significantly associated with NeP prevalence whether or not leg pain exists. Leg pain can increase the prevalence of NeP, especially when it contains a peripheral element.

LEVEL OF EVIDENCE

3.

Reliability among clinicians diagnosing low back-related leg pain

PURPOSE

To investigate agreement and reliability among clinicians when diagnosing low back-related leg pain (LBLP) in primary care consulters.

METHODS

Thirty-six patients were assessed by one of six physiotherapists and diagnosed as having either leg pain due to nerve root involvement (sciatica) or referred leg pain. Assessments were video recorded. In part one, the physiotherapists each viewed videos of six patients they had not assessed. In part two, videos were viewed by another six health professionals. All clinicians made an independent differential diagnosis and rated their confidence with diagnosis (range 50-100 %).

RESULTS

In part one agreement was 72 % with fair inter-rater reliability (K = 0.35, 95 % CI 0.07, 0.63). Results for part two were almost identical (K = 0.34, 95 % CI 0.02, 0.69). Agreement and reliability indices improved as diagnostic confidence increased.

CONCLUSION

Reliability was fair among clinicians from different backgrounds when diagnosing LBLP but improved substantially with high confidence in clinical diagnosis.

Outcome of decompression with and without fusion in spinal stenosis with degenerative spondylolisthesis in relation to preoperative pain pattern: a register study of 1,624 patients

BACKGROUND CONTEXT

Patients with spinal stenosis with concomitant degenerative spondylolisthesis (DS) and predominant back pain (PBP) have been shown to have inferior outcome after surgery. Studies comparing outcome according to preoperative pain predominance and treatment received are lacking.

PURPOSE

The purpose was to study if adding spinal fusion to the decompression in DS affects outcome in patients with PBP (back pain [BP] Visual Analog Scale [VAS] more than or equal to leg pain [LP] VAS) compared with predominant leg pain (PLP) (BP VAS less than LP VAS).

PATIENT SAMPLE

The Swedish Spine Register was used and included 1,624 patients operated for DS at the L4-L5 level.

OUTCOME MEASURES

Self-reported measures were used, including a VAS for BP and LP, the EuroQol-5D (EQ-5D), and the physical and mental component summaries of the Short-Form 36 to estimate health-related quality of life and the Oswestry disability index (ODI) to estimate function.

METHODS

Inclusion criterion was single-level DS operated on with either decompression only (D) or decompression and instrumented posterolateral fusion (DF). Based on preoperative LP and BP scores, the patients were assigned to one of the two groups: LP predominance or BP predominance. The patients completed the outcome protocol at 1- and 2-year follow-ups. Statistical analysis was performed using linear regression adjusting for multiple potential confounders.

RESULTS

In the adjusted outcome at the 1-year follow-up, patients with PLP reported a 7.9-mm more improvement on the VAS for BP with fusion, compared with D (95% confidence interval [CI], 0.7-15.2), p=.03. Despite more change in the fused group, the reported BP levels remained similar in the D versus decompressed and fused at the 1-year follow-up (28 vs. 24, p=.77). The patients with PBP benefited from adding fusion in terms of BP 7.1 (95% CI, 0.3-13.9, p=.04), LP 8.8 (2-15.7, p=.01), the ODI 5.7 (1.6-9.9, p=.006), and the EQ-5D 0.09 (1.7-0.02, p=.02) at the 1-year follow-up as the DF group reported greater change in the outcome compared with the D group. At the 2-year follow-up, no significant differences were found between D and decompressed and fused in either the LP or the PBP groups.

CONCLUSIONS

Patients with PBP operated with DF report better outcomes in terms of pain, function, and health-related quality of life than patients with D. Although these differences are significant on a group level, they may fail to reach minimal clinical significant difference. Patients with PLP report significantly more improvement in terms of BP with DF compared with D, but because of baseline differences in preoperative BP, these improvements may not be explained by the added fusion per se. At the 2-year follow-up, no significant differences were observed between the D and DF patients in either the PBP or PLP groups, but greater loss to follow-up in the DF groups could potentially bias these findings.