Lumbar Fusion in Utah Workers Compensation Patients: Changing Outcomes Across a Decade

Cuneo, Jessica G. PhD; DeBerard, M. Scott PhD; Wheeler, Anthony J. MS

doi: 10.1097/BRS.0000000000001964
Occupational Health/Ergonomics
Blog

Study Design. This study was a retrospective-cohort design involving a review of patient medical and cost records and a 2-year postsurgery follow-up outcome survey.

Objective. To evaluate the functional and cost outcomes associated with recent lumbar fusion surgeries in Utah workers and compare these outcomes with a comparable prior study cohort.

Summary of Background Data. Lumbar fusion performed on injured workers has dramatically increased over the past 2 decades and this likely coincided with the increased use of more advanced surgical instrumentation. Considering the recent changes in lumbar fusion surgery, there is a need to identify how patient outcomes have changed among injured workers.

Materials and Methods. Retrospective chart review and 2-year postsurgery follow-up survey of patient outcomes were performed. Postsurgical outcomes for this sample were compared with established norms for back pain patients and a previous cohort of compensated lumbar fusion patients obtained from Workers’ Compensation Fund of Utah.

Results. The current cohort evidenced a solid fusion rate of 89% and significant increase in the use of surgical instrumentation, particularly titanium fusion cages. Despite increased solid fusion rates, injured workers who have undergone lumbar fusion in Utah demonstrated equivalent and in some cases worse outcomes than those documented a decade ago. Specifically, there were significant increases in back pain dysfunction and narcotic medication usage in the current versus the past cohort. Medical and compensation costs for compensated lumbar fusion patients in Utah also significantly increased since the mid-1990s.

Conclusion. Over the past decade, injured workers who have undergone lumbar fusion in Utah showed an increase in solid fusion rates and costs without a corresponding improvement in patient outcomes.

Level of Evidence. 3

*Department of Psychology, Utah State University, Logan, UT

VA San Diego Healthcare System, San Diego, CA.

Address correspondence and reprint requests to M. Scott DeBerard, PhD, Department of Psychology, Utah State University, Logan, UT 84341; E-mail: scott.deberard@usu.edu

Received 18 January, 2016

Revised 23 July, 2016

Accepted 3 August, 2016

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

Workers’ Compensation Fund of Utah funds were received in support of this work.

No relevant financial activities outside the submitted work.

Article Outline

Lumbar fusion surgeries performed in the United States have increased dramatically over the past 2 decades.1–4 From 1992 to 2003, rates of lumbar fusion in the United States rose more than 250 percent.1 Costs for these procedures also rose substantially in the past decade, likely in part because of the use of more sophisticated surgical devices such as interbody fusion cages.1–5 Although surgical instrumentation is thought to improve the rate of arthrodesis, there is no evidence suggesting such devices are related to improved disability, complication or reoperation rates.1,4

Lumbar fusion outcomes are especially concerning for compensated workers. Patients with LBP who receive workers’ compensation have higher rates of lumbar fusion surgery and poorer outcomes than noncompensated patients.6–8 In Utah, a study of compensated lumbar fusion outcomes from 1990 to 1995 found that 36.1% of fusion patients reported worse pain and 35.4% indicated their overall quality of life was unimproved after surgery.7 One retrospective cohort study found that between 1994 and 2001, 1950 compensated workers who underwent lumbar fusion had an overall disability rate of 63.9%, a reoperation rate of 22.1%, and a complication rate of 11.8% at 2 years postsurgery.4 This study further demonstrated that use of fusion cages (alone and in combination with other instrumentation) was associated with increased complication and reoperation rates and higher risk of long-term disability as compared with bone-only fusions.4 Overall disability rates in this study remained similar to another study of compensated fusion patients conducted in the same state (Washington) several years before FDA approval of fusion cages.4

Given the increasing use of more sophisticated and costly surgical technologies in regard to lumbar fusion, it is important to examine if such technology is associated with differences, and particularly improvements, in multidimensional patient outcomes. This study evaluated functional patient and cost outcomes associated with lumbar fusion surgery and compared these more current outcomes with a prior study on Utah workers compensation patients.7 We expected solid arthrodesis rates and patient outcomes would have improved and that both compensation and medical costs would have increased across time.

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MATERIALS AND METHODS

Study Design

This study utilized a retrospective-cohort design that consisted of coding presurgical information documented in patient medical charts and administering a telephone outcome survey with patients at least 2 years postsurgery. The institutional review board at Utah State University approved this study and the Workers’ Compensation Fund of Utah (WCFU) provided permission to access patient medical records and contact patients for the follow-up survey.

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Patient Sample

Patients eligible for inclusion underwent elective lumbar fusion surgery between 1998 and 2007, had no presurgical diagnosis of vertebral fracture, and were at least 2-years postsurgery at time of the follow-up telephone survey. Lumbar fusion was the result of a low back injury sustained in the workplace. Using an administrative claims database, patients were identified via current procedural terminology (CPT) codes for lumbar fusion. Workers who were self-employed or covered by federal workers’ compensation programs were not included because of inaccessible data. The WCFU insures approximately 60% of Utah workers.

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Medical Chart Review

Presurgical medical record data were gathered via independent and standardized review of medical chart information and review of WCFU computer databases. The data abstractor was a trained doctoral student uninvolved with the treatment of patients in this study, who routinely met with authors to review and resolve coding discrepancies. The Medical Chart Review instrument was adapted from a previous instrument used for gathering information from the WCFU database in earlier spine outcome studies research.7,9 Arthrodesis was determined by a review of the operating surgeon's postoperative findings recorded in patient medical records. The operating surgeon's final opinion of arthrodesis was based on imaging studies and was typically included when the patient was nearing maximal medical improvement (MMI). The radiologists’ reports were also reviewed by an occupational physician to verify the surgeon's accurate interpretation. Cost data were gathered from WCFU administrative databases and represented actual reimbursement amounts. All costs were adjusted to year 2008 dollars from the year of the patient's respective index surgery using the US Bureau of Labor Statistics Consumer Price Index.

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Patient Outcome Survey

An objective outcome instrument and written interview script were adapted from the DeBerard et al7 study. After the interview script, participants were asked questions regarding their current functioning and quality of life since receiving their surgeries.

Patient satisfaction was determined using five closed-ended questions used in previous research on spine surgery outcomes that are specific to the lumbar fusion procedure.7,9 The items addressed patient satisfaction related to back/leg pain improvement, quality of life improvement, and satisfaction with their condition at time of follow up. These items used a response format ranging from a 3- to 7-point scale.

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Short Form Health Survey-36, Version 2

The Short Form Health Survey (SF-36v2)10 is a 36-item general health survey that assesses eight dimensions of health-related quality of life. The eight dimensions assessed by this measure include (1) physical functioning; (2) role physical; (3) bodily pain; (4) general health; (5) vitality; (6) social functioning; (7) role emotional; and (8) mental health. The eight subscales were also aggregated into Mental Health (MCS) and Physical Health (PCS) Component Summary scales.11

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Roland-Morris Disability Questionnaire

The Roland-Morris Disability Questionnaire (RDQ) is a 24-item self-report health status instrument intended to assess level of dysfunction in patients with LBP.12,13

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Stauffer-Coventry Index

The Stauffer-Coventry Index (SCI)14 is a measure used in previous research assessing outcomes after lumbar fusion surgery.7,9,14,15 The measure consists of four multiple response self-report questions regarding pain reduction, return to work, limitations of physical activities, and medication usage. In the current study, we collapsed the typical three categories of the Stauffer-Coventry Index scores (Good, Fair, Poor) into two categories (Percent Poor Outcome and Percent Fair to Good Outcome) for sake of parsimony. The “poor” categories were as follows: (i) pain relief = 0–25% improvement at time of follow up; (ii) employment = no return to work after surgery; (iii) physical limitations = severe restriction of physical activities; and (iv) medication usage = occasional or regular use of narcotic pain analgesics. The “good” categories were as follows: (i) pain relief = 26% to 100% improvement at time of follow up; (ii) employment = return to lighter or previous work after surgery; (iii) physical limitations = moderate to minimal or no restriction of physical activities; and (iv) medication usage = regular use of nonnarcotic analgesics to occasional or no use of nonnarcotic analgesics.

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Procedures for Outcome Survey

The patient outcome survey used in the telephone interview was administered at the initial time of contact unless participants requested to not participate or to participate at a later scheduled time. Three doctoral students who had no treatment contact with the patients conducted the telephone outcome surveys. The interviewers were trained in basic interviewing skills and provided with a detailed written script to follow when conducting the survey.

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Comparison to Previous Cohort of Compensated Utah Lumbar Fusion Patients

Functional outcomes and cost data from the current cohort were compared with a previous cohort of compensated lumbar fusion patients from the same insurance provider.7 Patients in the previous cohort underwent elective lumbar fusion for a work-related spine injury between 1990 and 1995. Both studies employed the same retrospective-cohort design and selection criteria. The chart review procedures were quite similar with major differences involving inclusion of some new variables in the recent cohort. The telephone surveys were also quite similar across the two cohorts with the exception of some additional items and an updated outcome instrument in the more recent cohort. Inter-rater reliabilities for the chart review and outcome surveys were very high (>0.94) across both cohorts.

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RESULTS

Population and Sample

The present cohort included 245 patients of whom 110 were contacted for follow up (45%). This follow-up rate is commensurate with our other published retrospective-cohort studies of compensated lumbar fusion patients.7–9 Patients’ primary diagnosis given by the operating surgeon according to the operative report included disc herniation (39.2%), degenerative disc disease (30.2%), spondylolisthesis (13.5%), spinal stenosis (7.8%), radiculopathy (3.3%), and other (5.7%). Table 1 provides demographic and procedural information about the current and previous patient cohorts. A relevant t test or χ2 test and effect size was ascertained for each comparison. Patients in the current cohort were slightly older (4.1 years), more likely to have a history of depression, and more likely to have received instrumentation. The average time from surgery to follow up was also longer in the current cohort (23 months).

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Outcome Survey Results

Table 2 displays results of the SF-36 (v.2) outcomes survey relative to a sample of back pain patients presenting with sciatica and also relative to general population norms.10 Substantial differences were seen between the current study sample and the norms of back pain patients in the areas of physical functioning (d = −0.81), role functioning (d = −0.68), and the physical component summary (d = −0.72). Social and emotional functioning were also reported to be much lower in the fusion patient sample compared with the back pain/sciatica norms (d = −0.45 and d = −0.44, respectively). It should be noted that the prior study cohort was given a different quality of life measure (SF-20) and direct comparisons between studies were not possible for these variables. However, in general, health-related quality of life for both samples appeared substantially below general population and back pain specific normative groups.

Results of the patient satisfaction items are presented in Table 3. Approximately, 46% of patients indicated they were “somewhat” to “extremely dissatisfied” with their back condition after surgery, although nearly 70% reported they would have their fusion surgery again; 36.6% of patients indicated their quality of life was worse than expected after surgery, whereas half (51.5%) reported their back pain was worse after surgery. These measures of patient satisfaction were commensurate with findings from the prior cohort.

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Functional, Clinical, Disability, and Cost Outcomes

Table 4 contains comparisons of outcomes across both cohorts (including t or χ2 values and relevant effect sizes). As may be seen in Table 4, RDQ average scores were slightly higher in the current cohort and this is reflective of higher back pain related dysfunction. There were also statistical significant differences in the SCI-Medication Usage scale with the current cohort have 23% more patients using occasional or regular narcotic medications after surgery. Percent solid arthrodesis was statistically-significantly higher in the current cohort (89.1%) versus the prior cohort (71.9%). Figure 1 depicts the arthrodesis rates in 2-year increments across the two study cohorts. As may be seen, there was trend for increasing rates of arthrodesis in the first cohort with more of a leveling off in the current cohort. Average compensation costs were approximately $22,987 higher in the current versus the prior cohort (57% increase). Average medical costs increased by $67,434 (153%) in the current versus initial cohort.

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DISCUSSION

Findings from our analyses show that since the early to mid-1990 s, the rates of solid arthrodesis increased markedly (72%–89%) for injured workers who underwent lumbar fusion in Utah. This rate appeared to increase over time and in particular since 1996 after the FDA approval of fusion cages. The use of instrumentation also increased to 99.1% in the current cohort versus 83.7% in the prior cohort. Fusion cages were used either alone (7.3%) or in conjunction with pedicle screws (43.6%) in 51% of the instrumented cases. Despite a substantial increase in solid fusion rates and advances in surgical technology, compensated patients in Utah evidenced mostly equivalent satisfaction and functional outcomes than those documented over a decade ago. The exceptions to this pattern were higher RDQ scores and increased usage of narcotic pain medications. Finally, both total compensation and medical costs increased significantly across the two cohorts. This is one of the first studies that examined longitudinal patterns of lumbar fusion outcomes within a single state and thus provides a unique perspective for the spine and general health care community.

In the United States, the prevalence of lumbar fusion surgery has grown dramatically, particularly in the treatment of degenerative lumbar spine disorders. Both the increase in prevalence and expansion of indications for lumbar fusion is a controversial issue in the literature. This is complicated by published guidelines by neurosurgical and orthopedic professional societies that are vague and are subjected to a wide range of interpretations. In our current study alone, over two thirds of the cases had primary diagnoses of degenerative disk disease or disc herniation. This is concerning given the limited evidence of improved outcomes for fusion surgery over noncompression surgery for diagnoses other than spinal instability.16

It is notable that our findings were evident in a relatively homogenous sample of injured workers in Utah. Consideration of how geographic regions with different surgical practice trends and compensation systems impact the number of fusion operations performed is also relevant. Recent studies have reported an increase in lumbar fusion in some areas by as much as 77% in a 5-year period and 267% in 11 years.1,16 Potential factors influencing geographic variation may include differences in clinical training, clinical decision making, and access to care considerations. To some extent, the disparity may also be explained by surgeon preference; which may in turn be influenced by financial incentives that can be more favorable for lumbar fusion versus other spine procedures.17

The increase in narcotic medication use among fusion patients is another concern. Nationwide from 1997 to 2004, patients with back-related disorders showed a 108% increase in opioid prescriptions for pain with a 423% increase in medical costs associated with such medications.18 For the current study, patients’ narcotic use is slightly higher than national norms of low back pain patients, which were approximately 45% in 2006.19 Although there is no evidence suggesting that narcotic analgesic use before lumbar fusion predicts outcomes, a primary risk factor of increased narcotic use includes work related back injury.20 There is also evidence that long-term treatment of pain with narcotic medication is known to have a significant negative impact on all aspects of quality of life.20,21 Although the current study did not evaluate duration of medication use, this may be an important variable to address in future research.

A central limitation of this study is the possibility of methodological bias across the two cohorts. In other words, the differences observed in outcomes across the two cohorts might not be because of changes in surgical technology/skill but rather caused by selection, instrument, or extraneous sources of bias. This possibility can be somewhat tempered by the fact that identical retrospective-cohort designs and inclusion criteria were utilized across cohorts. There were some minor differences in the presurgical chart review and outcome instruments although we do not believe these changes were likely sufficient to account for observed outcome differences. We also did not identify any significant changes regarding the Workers’ Compensation Fund of Utah's approval, reimbursement, or management procedures regarding lumbar fusion across the two cohorts. Another important limitation is the low follow-up rate in the most recent cohort. In the past decade, society's reliability on landlines has dramatically declined with more people using wireless devices as their primary mode of communication, particularly among younger adults.22 As the percentage of cell phone use increases, health researchers have reported more difficulty collecting telephone survey data because of higher costs and the tendency to screen calls.23 Despite the follow-up differences, nonresponse bias checks of each cohort did not suggest any differential bias in terms of measured presurgical variables across responders versus nonresponders. Another limitation was the inclusion of data from only one US State with a quite homogenous population in terms of ethnic and religious diversity. It is unknown if the current findings can be generalized to other states with different compensation systems.24 Another study of occupational low back injuries demonstrated racial differences in both low back pain diagnosis and referral for spine surgery and it was not possible to explore such issues in the current study.25

There are several recommendations for future research in the area of lumbar fusion, particularly in terms of worker's compensation populations. Because of the high costs associated with lumbar fusion and the potential for less costly nonsurgical approaches to be equally effective, it might be beneficial to conduct comparative effectiveness studies of both approaches in the workers’ compensation context. Further, as has been shown in noncompensated patients, less invasive surgeries such as decompression alone may offer equivalent outcomes to fusion in compensation patients with less costs and surgical complications.26

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Key Points

* This study evaluated functional patient and cost outcomes associated with lumbar fusion surgery and compared these outcomes with a prior study of Utah workers compensation patients.

* Although findings showed an increase in solid fusion rates, advanced surgical technology, and overall costs, patients functional and disability outcomes did not improve and in some cases worsened as compared to the prior study.

* Although some compensated workers may benefit from lumbar fusion, this study highlights the importance of providers to use more discretion when recommending this procedure as a treatment option for injured workers.

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References

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Keywords:

disability; instrumentation; longitudinal cohort comparison; lumbar arthrodesis; lumbar fusion outcomes; medical costs; workers’ compensation

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