Abstract
Introduction
The effect of pain on HRQoL scores in ASD patients is not well studied. Disability is a major factor on decision and outcomes. On the other hand, little is known about the effect of perceived and reported pain on these parameters, especially in the elderly population. We hypothesized that baseline back and leg pain would not affect the treatment decision whereas may have a negative effect on outcomes.
Research question
To determine the correlation between preoperative ODI and VAS scores; and to identify the effect of baseline VAS score on treatment decision and ODI improvement following treatment.
Material and methods
In this retrospective study, patients with a follow-up duration of minimum 2 years were enrolled from a prospective multicentric ASD database. Pearson and Spearman correlation tests were used to evaluate the correlation between ODI and VAS scores; univariate binary logistic regression method was used to analyze the effect of VAS on treatment decision as well as the outcomes.
Results
1050 patients (mean age 48.2) were analyzed. Baseline ODI and back, leg pain VAS scores were significantly correlated (P < 0.001). One unit increase in baseline back and leg pain VAS scores, increased the probability of improvement in ODI by 1.219 (P = 0.016) and 1.182 times (P = 0.029), respectively in surgically treated patients; and reduced it by 0.894 times (P = 0.012) for conservatively treated patients. For patients >70 years old, one-unit increase in baseline leg pain VAS score increased the probability of deciding on surgical treatment by 1.121 times (p = 0.016).
Discussion and conclusions
Preoperative back and leg pain VAS scores were found to be significantly correlated with the preoperative ODI scores. Additionally, preoperative baseline back and leg pain VAS scores were useful in predicting the improvement in disability as assessed by ODI. Another important finding was that, higher baseline leg pain (but not back pain) VAS scores increased the rate of elderly patients preferring surgical treatment.
Keywords: VAS, ODI, Adult spinal deformity, HRQOL, Scoliosis
Highlights
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To determine the correlation between preoperative ODI and VAS scores.
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To identify the effect of baseline VAS score on treatment decision and ODI improvement following treatment.
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To predict the improvement in disability as assessed by ODI preoperative baseline back and leg pain VAS scores.
1. Introduction
In addition to growth of the aging population, increased awareness of quality of life has made adult spinal deformity (ASD) an important health care concern. As a result, adult patients, especially the elderly, seek health care for treatment for disabling spinal conditions (Daubs et al., 2007). First-line treatment for symptomatic ASD patients presenting with pain and disability without progressive neurological deficit usually involves non-operative treatment strategies, such as physical therapy, injections, non-steroidal anti-inflammatory drugs and/or narcotic analgesics (Glassman et al., 2006; Smith et al., 2011). When it is indicated, instrumented arthrodesis of the spine is widely used to correct the spinal deformity and restore balance and to improve pain and overall HRQoL (Kondo et al., 2017). In the surgically treated ASD group, treatment satisfaction has been shown to be moderately correlated with the preoperative disability, measured by the Oswestry Disability Index (ODI) and Short Form-36 Physical Component Summary (SF36 PCS) (Hamilton et al., 2017; Faraj et al., 2018). Also, satisfaction was not associated with radiographic parameters or the presence or absence of peri-operative complications (Hamilton et al., 2017; Faraj et al., 2018). Self-assessment disability scales were found to be more useful in evaluating preoperative disability than pain severity scales, radiographs, CT scans and MRI examinations (Sigmundsson et al., 2011).
Spine healthcare professionals always want to have decision-making tools based on objective criteria when deciding surgery in patients with ASD. Using health-related quality of life scales (HRQoL) to assess disability (e.g., ODI) serves this purpose; however, little is known whether this also applies to back or leg pain scales (i.e., back or leg pain Visual Analogue Scale (VAS)) (Acaroglu et al., 2016). In this regard, DeVine et al. in their systemic review found that the correlation between ODI and VAS was not strong in patients with ASD (DeVine et al., 2011). Gronblad et al., analyzed the correlations between ODI, PDI (Pain Disability Index) and VAS in patients with LBP and found that the correlations between ODI and PDI were strong (r = 0.83) whereas, correlations between VAS scores and ODI were not as strong (r = 0.62). (Grönblad et al., 1993).
We noticed a gap in our knowledge in that it is not clear whether the disability in the ASD population is based on or even, affected by the perception of pain and if so, to what extent. In this context, it may be important to analyze the relationship between perceived disabilities and perceived pain levels in these patients, i.e., is pain the only cause of their disability? If this is the case, the correlation between disability measure (ODI) and pain measure (VAS leg/back) should be very strong. Another valid question in the same context is on the effects of these factors on decision-making in surgical treatment, predominantly by patients, but to some extent by surgeons as well. Can the surgery decision be significantly affected by pain; if so, do both back and leg pain contributes to this effect? And finally, what may be the effect of initial pain on treatment (surgical or non-surgical) results?
This current study was performed to analyze the correlation between preoperative and postoperative ODI and VAS scores in adult patients with spinal deformity; and to identify the effect of baseline VAS score on treatment decision and ODI improvement. We hypothesized that baseline back and leg pain do not affect the treatment decision but negatively affect the outcomes.
2. Materials and methods
In this retrospective study on prospectively collected ASD data, patients were enrolled from an international prospective multicentric ASD database. Patients with a follow-up duration of at least 2 years were selected according to the following criteria: age >18 years and scoliosis >20° and/or sagittal vertical axis (SVA) > 5 cm and/or pelvic tilt >25° and/or thoracic kyphosis >60°. Patients’ demographic data (age, gender, co-morbidities and body mass index (BMI)), baseline, post-treatment and follow-up ODI and VAS scores (leg and back), radiological parameters (Sagittal vertical axis (SVA), T2-T12 kyphosis, coronal balance, major curve Cobb angle, lordosis gap (L Gap) (Aurouer et al., 2009), global tilt (Obeid et al., 2016), and T1 sagittal tilt) were analyzed. Patients were stratified with deformity etiology (idiopathic or degenerative) and treatment method (surgical or non-surgical).
2.1. Visual Analogue Scale for pain
The VAS represents a method of assessment of a feeling. It consists of a 100-mm long line (the designated dolorimeter); the left end signifying no pain and the right unbearable and unprecedented pain. It requires the transfer of a sensation into another dimension. A virtual continuous parameter is artificially reified at a certain point and transferred into a digital system (Ohnhaus and Adler, 1975).
2.2. Oswestry low back Pain Disability Index
The ODI was developed in a specialist referral clinic for patients with chronic LBP (Fairbank et al., 1980). The item selection was based on an interview designed to assess limitations in various activities. It is a self-reported questionnaire of a patient's perceived disability based on 10 areas of pain and daily activities (pain intensity, personal hygiene, lifting, walking, sitting, standing, sleeping, sexual activity, social activity and travelling). Each section is scored on a 6-point scale (0–5), with 0 representing no limitation and 5 representing maximal limitation. The sub-scales combined add up to a total maximal score of 50. The score is then doubled and interpreted as a percentage of the patient-perceived disability (the higher the score, the greater the disability). In cases where patients did not answer all the 10 sections, the sum score of the answered sections are divided by the number of completed sections followed by multiplication by ten for purposes of the normalization of the score (Grotle et al., 2003).
2.3. Statistical analysis
The main aim of this study related to statistical analysis was to find out the correlation between back and leg pain VAS scores with preoperative ODI scores and postoperative ODI improvement in surgically or non-surgically treated patients. A univariate binary logistic regression method was used using dependent and independent variables listed above.
Before the correlation analysis the type of distribution behavior of the variables, whether homogenous or not, was tested first. According to the distribution behavior, Pearson or Spearman correlation coefficient was used to evaluate the correlation between ODI and VAS scores and the correlation between the baseline back and leg pain VAS scores with the postoperative ODI scores improvement. Type-I error rate was taken as α = 0.05 for statistical significance for all analyses.
3. Results
1050 patients (887 females and 163 males), with a mean age of 48.2, were enrolled from the ASD database. While 334 of these patients had a degenerative etiology, 718 had idiopathic deformity (Table 1). Six hundred and ninety-eight of them received non-surgical treatment whereas 352 of them underwent surgery. Spearman's correlation coefficient (rho) was 0.459 for baseline backpain VAS score and baseline ODI score; and 0.443 for baseline leg pain VAS score and baseline ODI score. Correlations between baseline ODI score and baseline back and leg pain VAS scores were found as statistically significant (P < 0.001) (Table 2).
Table 1.
Characteristics of ASD patients.
| n, Mean ± SD, min-max | |
|---|---|
| Age, years | 1035, 48.2 ± 19.9, 18-89 |
| BMI | 1010, 24.01 ± 4.79, 15.40–54.60 |
| Sex | n (%) |
| Female | 887 (84.5) |
| Male | 163 (15.5) |
| Diagnosis | n (%) |
| Degenerative | 332 (31.6) |
| İdiopathic | 718 (68.4) |
| Treatment | n (%) |
| Surgical | 352 (33.5) |
| Non-surgical | 698 (66.5) |
| Baseline Radiological parameters | n, Mean ± SD, min-max |
| T2-T12 kyphosis | 972, 39.12 ± 16.64, 1-98 |
| Major curve Cobb angle | 991, 43.82 ± 20.05, 4-151 |
| Lordosis gap (L Gap) | 923, 16.93 ± 14.48, 0.04–83.02 |
| Global tilt | 885, 21.93 ± 15.29, 1-70 |
| T1 sagittal tilt | 890, 4.89 ± 3.26, 0-23 |
| SVA | n (%) |
| 0 | 650 (69.3) |
| + | 201 (21.4) |
| ++ | 87 (9.3) |
| Coronal balance | n (%) |
| D | 370 (36.2) |
| L | 231 (22.6) |
| N | 295 (28.8) |
| T | 127 (12.4) |
| Baseline scores | n, Mean ± SD, min-max |
| ODI | 1000, 30.18 ± 20.70, 0-100 |
| Back pain VAS | 1027, 5.48 ± 2.75, 0-10 |
| Leg pain VAS | 1027, 3.12 ± 3.28, 0-10 |
| 1st year scores | |
| ODI | 536, 25.46 ± 18.69,0-82 |
| Back pain VAS | 549, 4.27 ± 2.93, 0-10 |
| Leg pain VAS | 549, 2.63 ± 2.94, 0-10 |
Table 2.
Correlations among baseline ODI and baseline back and leg pain VAS.
| Baseline leg pain VAS | Baseline ODI | ||
|---|---|---|---|
| Baseline back pain VAS | Rho | 0.289∗∗ | 0.459∗∗ |
| P | < 0.001 | < 0.001 | |
| n | 339 | 329 | |
| Baseline leg pain VAS | rho | 0.443∗∗ | |
| p | < 0.001 | ||
| n | 329 | ||
∗∗Correlation is statistically significant at the 0.01 level.
The mean age of the surgically treated 352 patients (287 females and 65 males) was 53.0 years. 165 of them had spinal deformities due to degenerative spine conditions and 187 had due to idiopathic etiology (Table 3). Univariate logistic regression test results showed for surgically treated patients that, one unit increase in baseline back and leg pain VAS score increased the probability of improvement in ODI by 1.219 times (P = 0.016) and 1.182 times (P = 0.029), respectively (Table 4, Table 5).
Table 3.
Characteristics of surgically treated patients.
| n, Mean ± SD, min-max | |
|---|---|
| Age, years | 352, 53 ± 20.10, 18-86 |
| Sex | n (%) |
| Female | 287 (81.5) |
| Male | 65 (18.5) |
| Diagnosis | n (%) |
| Degenerative | 165 (46.9) |
| İdiopathic | 187 (53.1) |
| Baseline scores | n, Mean ± SD, min-max |
| ODI | 331,40.02 ± 20.67, 0-98 |
| Back pain VAS | 339, 6.19 ± 2.59, 0-10 |
| Leg pain VAS | 339, 4.06 ± 3.33, 0-10 |
| 1st year scores | n, Mean ± SD, min-max |
| ODI | 191, 28.76 ± 17.98, 0-76 |
| Back pain VAS | 195, 3.44 ± 2.66, 0-10 |
| Leg pain VAS | 195, 2.28 ± 2.77, 0-10 |
Table 4.
Univariate logistic regression test results for back pain baseline VAS scores for surgically treated patients.
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| ODI improvement | 1.219 (1.038–1.431) | 0.016 |
Table 5.
Univariate logistic regression test results for leg pain baseline VAS scores for surgically treated patient.
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| ODI improvement | 1.182 (1.017–1.373) | 0.029 |
In the non-surgical group, there were 698 patients (600 females and 98 males), 167 with degenerative and 531 with idiopathic spinal conditions. The mean age among this group was 45.7 years (Table 6). The univariate logistic regression test results, one unit increase in baseline back pain VAS score, reduced the probability of improvement in ODI by 0.894 times.
Table 6.
Characteristics of non-surgically treated patients.
| n, Mean ± SD, min-max | |
|---|---|
| Age, years | 683, 45.75 ± 19.49, 18-89 |
| Sex | n(%) |
| Female | 600 (86) |
| Male | 98 (14) |
| Diagnosis | n(%) |
| Degenerative | 167 (23.9) |
| İdiopathic | 531 (76.1) |
| Baseline scores | n, Mean ± SD, min-max |
| ODI | 669, 25.31 ± 18.93, 0-100 |
| Back pain VAS | 688, 5.13 ± 2.77, 0-10 |
| Leg pain VAS | 688, 2.66 ± 3.15, 0-10 |
| 1st year scores | n, Mean ± SD, min-max |
| ODI | 345, 23.63 ± 18.85, 0-82 |
| Back pain VAS | 354, 4.72 ± 2.97, 0-10 |
| Leg pain VAS | 354, 2.82 ± 3.02, 0-10 |
P = 0.012), while baseline leg pain VAS score had no effect on ODI improvement (P > 0.05) (Table 7, Table 8).
Table 7.
Univariate logistic regression test results for back pain baseline VAS scores for non-surgically treated patients.
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| ODI improvement | 0.894 (0.819–0.975) | 0.012 |
Table 8.
Univariate logistic regression test results for leg pain baseline VAS scores for non-surgically treated patients.
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| ODI improvement | 0.960 (0.891–1.035) | 0.292 |
17.2% of the ASD patients (151 females and 30 males) were over 70 years old. 80.7% of them had degenerative deformity while 19.3% had idiopathic deformity. 28.7% of them underwent surgical treatment and 71.3% had conservative treatment (Table 9). Univariate logistic regression test results showed that baseline back pain VAS score had no effect on deciding surgical treatment for elderly population (patients with age ≥70) (Table 10). On the other hand, It was seen that one unit increase in baseline leg pain VAS score increased the probability of deciding on surgical treatment for elderly population by 1.121 times (p = 0.016) (Table 11).
Table 9.
Characteristics of the elderly patients (age >70 years).
| n, Mean ± SD, min-max | |
|---|---|
| Age, years | 181, 75.54 ± 4.33, 70-89 |
| Sex | n (%) |
| Female | 151 (83.4) |
| Male | 30 (16.6) |
| Diagnosis | n (%) |
| Degenerative | 146 (80.7) |
| İdiopathic | 35 (19.3) |
| Treatment | |
| Surgical | 85 (47) |
| Non-surgical | 96 (53) |
| Baseline scores | n, Mean ± SD, min-max |
| ODI | 179, 44.70 ± 17.59, 4-98 |
| Back pain VAS | 178, 6.38 ± 2.26, 0-10 |
| Leg pain VAS | 178, 4.41 ± 3.27, 0-10 |
| 1st year scores | n, Mean ± SD, min-max |
| ODI | 73, 35.98 ± 18.69, 2-82 |
| Back pain VAS | 74, 4.27 ± 3.10, 0-10 |
| Leg pain VAS | 74, 3.12 ± 3.09, 0-10 |
Table 10.
Univariate logistic regression test results for back pain baseline VAS scores on deciding surgical treatment for elderly population (patients with age ≥70).
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| Surgery group | 1.071 (0.939–1.222) | 0.307 |
Table 11.
Univariate logistic regression test results for leg pain baseline VAS scores on deciding surgical treatment for elderly population.
| Dependent variable | OR (95% C.I.) | P |
|---|---|---|
| Surgery group | 1.121 (1.022–1.230) | 0.016 |
4. Discussion
This study was performed on a cohort of adult patients with spinal deformities to find out whether the back and leg pain VAS scores correlated with the preoperative ODI scores; and to investigate the effects of the preoperative VAS scores on patients’ treatment decision and on ODI improvement following surgical and non-surgical treatment. Our results showed that, baseline back and leg pain VAS scores were significantly correlated with the preoperative ODI scores. The univariate logistic regression tests showed for surgically treated patients that, one unit increase in baseline back and leg pain VAS score increased the probability of improvement in ODI by 1.219 times and 1.182 times respectively; and for patients treated non-surgically one unit increase in baseline back pain VAS, reduced the probability of improvement in ODI by 0.894 times, while baseline leg pain VAS had no effect on ODI improvement. In elderly patients, one unit increase in baseline leg pain VAS score increased the probability of deciding on surgical treatment by 1.121 times, whereas baseline back pain VAS score had no effect on treatment decision.
As previously reported in the literature, VAS scores and ODI were moderately correlated with each other (Faraj et al., 2018). This significant association was not unexpected because the cause of disability in elderly patients with ASD was mostly limited range of motion due to pain or pain rather than spinal deformity, but the level of correlation (moderate) was quite lower than expected. The most frequent symptom of patients with ASD is low back pain, which is the main reason of disability in daily life of these individuals whose average age is quite high (Lonergan et al., 2016). The ODI scoring system evaluates disability not only by pain intensity, but also by personal hygiene, lifting, walking, sitting, standing, sleeping, sexual activity, social activity, and travelling (Fairbank and Pynsent, 2000). The frequency of these activities and the way they are carried out may vary for each individual; moreover, the perception of restriction in each area may vary from person to person, even the actual level of limitation is equal. These differences between individuals may be the reason for the moderate correlation between scores.
Higher improvement in postoperative ODI scores with worse baseline HRQoL scores have been demonstrated previously in several studies (Ames et al., 2019). We also found that patients with higher preoperative back and leg pain VAS scores, worse baseline condition in terms of disability, showed higher improvement in postoperative ODI scores. This finding indicates a significant correlation of the back and leg pain VAS scores with the ODI scores.
It was previously reported that the results of nonoperative treatment methods in ASD were worse than operative treatment (Acaroglu et al., 2016; Acaroglu and European Spine Study Group, 2016; Acaroglu et al., 2017). Patients who did not undergo surgery had unchanged or worse ODI scores compared to their baseline scores. This knowledge was also supported by the present study, improvement rate in ODI scores were lower in patients with higher baseline back pain VAS scores; however leg pain VAS scores were not correlated with ODI improvement in this group of patients.
The improvement in the ODI score may not always be detectable by the patient, even with a statistically significant change in ODI after surgery. The minimum clinically important difference (MCID) and minimum detectable change (MDC) values of ODI were reported as 14.31 and 10.65 respectively, in the study of Yüksel et al. (Yuksel et al., 2019) However, very low VAS improvements may be reported by patients after surgery. A patient who describes an improvement in pain of up to almost 10 points actually experiences an improvement in ODI score below the MCID and MDC values (since one unit change in baseline VAS score changes the ODI improvement by about 1.2 times in our study). This can be highlighted as the superiority of VAS assessment over ODI scoring in the evaluation of postoperative patients.
Despite the improvement in the ODI scores over MCID values, dissatisfaction after ASD treatment is a common problem. Carragee and Cheng described minimum acceptable outcome concept for satisfaction following surgery (Carragee and Cheng, 2010). Reflecting the patients’ clinical condition only by pain may be insufficient, as only by ODI evaluation. On the other hand, Ruiz and colleagues showed that ODI correlated better with extremes of lumbar motion and activities of daily living compared to VAS pain scores (Ruiz et al., 2014).
Numerous factors have been examined for the treatment decision in ASD. Fujishiro et al. reported that, worsening HRQOL and in particular perception of worsening appearance based on SRS-22 self-image domain guided surgical treatment in the ASD population. In addition, pain and disability increased the rate of surgical treatment selection in older patient, while greater coronal deformity was more important for younger patients. Finally the lack of lumbar lordosis in relation to pelvic incidence was a strong driver to pursue surgical treatment in ASD patients (Fujishiro et al., 2018). Adult spinal deformity surgical decision-making score was developed to guide the decision-making process for ASD patients aged above 40 years (Fujishiro et al., 2019, 2020). In the present study, higher baseline leg pain VAS score was found to have a significant effect on surgical treatment decision in elderly patients. As a difference, pain parameter was directly evaluated by VAS score, not as an integral part of SRS-22, ODI, and NRS. It gave us the opportunity to see the effect of pain more clearly. In elderly patients, one unit increase in baseline leg pain VAS score increased the probability of deciding on surgical treatment by 1.121 times, whereas baseline back pain VAS score had no effect on treatment decision.
The surgery for ASD is not always performed to relieve pain. Some of the procedures are performed to correct the deformity, decompress the spinal canal, correct sagittal imbalance, improve functionality or prevent progression of the deformity, especially in younger adults. This means that VAS or ODI scores should not always be expected to improve after surgery, and even some patients do not have any pain before and after the surgery, but their postoperative ODI scores are worse. Therefore, studies investigating the correlation between VAS and HRQoL measurements should be conducted based on single unique groups with similar demographic and surgical indication characteristics.
4.1. Limitations
The most significant limitation of this study is its multicenter nature which may lead to variation in demographic characteristics of patients and treatment modalities that may have caused different outcomes, especially in regard to treatment choice. Also, radiographic measurements and measurement of HRQoL scores were made by different staff in different countries and in different institutes. Another limitation is the miscellaneous diagnoses of the patients enrolled in the ESSG registry.
5. Conclusions
In adult patients with spinal deformity, preoperative back and leg pain VAS scores were found to be significantly correlated with the preoperative ODI scores. Additionally we found that, preoperative baseline back and leg pain VAS scores were useful in predicting the improvement in disability, rated by ODI. However, the outcomes after conservative treatment methods were estimated only by the baseline back pain VAS scores, which were found to be inversely correlated with improvement in disability. In addition, it was shown that, higher baseline leg pain VAS scores in elderly patients (age >70 years) increased the rate of patients choosing surgical treatment.
Declaration of competing interest
The authors of this manuscript have no competing interests that influence the results and discussion of this paper.
Acknowledgement
This study as well as the intellectual owner of the database it is based on, The European Spine Study Group (ESSG), are funded by a research grant from Depuy-Synthes Spine.
Contributor Information
Prashant Adhikari, Email: adhikariprashant@hotmail.com.
Engin Çetin, Email: enginctn@yahoo.com.tr.
Mehmet Çetinkaya, Email: drcetink@gmail.com.
Vugar Nabi, Email: drvugarnabizade@gmail.com.
Selcen Yüksel, Email: Selcenpehlivan@yahoo.com.
Alba Vila Casademunt, Email: albavilacasedemunt@gmail.com.
Ibrahim Obeid, Email: Ibrahim.obeid@gmail.com.
Francesco Sanchez Perez-Grueso, Email: perezgrueso@gmail.com.
Emre Acaroğlu, Email: acaroglue@gmail.com.
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