Reliability and validity of Turkish versions of Sciatica Bothersomeness and Sciatica Frequency Index

Abstract

BACKGROUND:

The Sciatica Frequency Index (SFI) and Sciatica Bothersomeness Index (SBI) are two separate indices scored for both the bothersomeness and frequency of radiating symptoms. There is no Turkish scale used specifically for sciatica.

OBJECTIVE:

We aimed to translate SBI and SBI in Turkish and investigate the reliability and validity of these indices.

METHODS:

A total of 80 patients with lumbar disc herniation (LDH) were prospectively included. Construct validity was assessed by comparing the SBI and SFI with subscales of Short Form 36 (SF-36), back and leg Numeric Rating Scale (NRS) and Roland Morris Disability Questionnaire (RMDQ). Reliability was assessed by internal consistency (Cronbach’s alpha) and test-retest reliability.

RESULTS:

A weak correlation was found between SBI/SFI, back NRS and SF-36 subgroups while a moderate correlation was found between SBI/SFI, RMDQ and leg NRS. The SBI and SFI had high internal consistency measured by Cronbach’s alpha (0.76 and 0.73). Test-retest reliability of the SBI and SFI were 0.95 (95% CI: 0.92–0.97) and 0.95 (95% CI: 0.92–0.97) respectively, indicating excellent reliability.

CONCLUSION:

The Turkish versions of the SFI/SBI are a valid and reliable tool supporting their usability in patients with LDH-induced sciatica.

Keywords

Lumbar region sciatica reliability and validity

1. Introduction

Sciatica can cause pain, paresthesia or weakness in the patient’s sciatic nerve distribution and can also be associated with the lumbosacral nerve roots. In clinical practice, any low back pain or radicular leg pain is often mistakenly described as sciatica. Sciatica is specific to pain that is a direct result of sciatic nerve or sciatic nerve root pathology [1]. It is a common cause of low back pain with a prevalence ranging from 1.2 to 43% in the general population [2]. While disc herniation, spinal stenosis, spondylolisthesis, malignancy, epidural hematoma or epidural abscess may cause sciatica [3], approximately 90% of cases are due to disc herniation [4].

Lumbar disc herniation (LDH)-induced sciatica is characterized by pain, numbness, and weakness due to the displacement of the disc material. The nerve roots and dorsal root ganglia are compressed and inflamed by the herniated disc material [5]. This nerve root or ganglia involvement may cause lower back and leg pain, thereby reducing the functions of an individual [6]. As a result, sciatica decreases employee performance and causes high socioeconomic burden in the society [7].

Although there are indices that evaluate low back pain and disability due to LDH in Turkey, to the best of our knowledge, there is no index that evaluates symptoms due to sciatica [8, 9, 10]. The Sciatica Frequency Index (SFI) and Sciatica Bothersomeness Index (SBI) are two separate indices, each consisting of four questions, scored for both the bothersomeness and the frequency of radiating symptoms [11]. The SBI and SFI have been validated and reliable for Norwegian, Greek and Gujarati languages and are used in daily clinic [12, 13, 14]. These indices have been used in many studies [15, 16, 17] and three of the items, which are leg pain, numbness in foot and pain affecting sitting positions, are included in the North American Spine Society outcome instrument [18]. The lifetime prevalence of low back pain ranges from 44 to 79% with an annual prevalence of 35.99% in Turkey [19]. Although no study has been performed on the frequency of sciatica in Turkey, its frequency in the literature increases up to 40% in other societies [2]. This result has a negative effect on the country’s economy both in terms of health expenditures and loss of production associated with morbidity and mortality [20]. To date, no Turkish versions of the indices have been reported.

In our pain medicine clinic, many patients are treated and followed due to sciatica and, therefore we need reliable and valid indices which can evaluate these symptoms. We believe that these indices, which would be used in the treatment and follow-up of sciatica patients, would somewhat prevent unnecessary drug administration and unnecessary imaging tests. Therefore, in the present study, we aimed to translate SFI and SBI in Turkish and investigate reliability and validity of these indices. Thus, we would be able to evaluate the functional results of Turkish-speaking patients for clinical studies and patient follow-up.

2. Methods

2.1 Measures

Demographic data of the patients such as weight, height, age, sex, and education status were collected. The leg pain and back pain severity was assessed by using the Numeric Rating Scale (NRS).

The SBI and SFI are an index that examines four symptoms: The first question measures leg pain, the second question is tingling or numbness in the foot, leg or groin, the third question is weakness in the leg/foot and the fourth and final question is for back or leg pain while sitting. For SBI each question is scored from 0 (Not bothersome) to 6 (Extremely bothersome) and for SFI each question is scored from 0 (Not at all) to 6 (Always). The total score of SBI and SFI ranges from 0 to 24 and it takes approximately 1 minute to complete [11].

The Short Form 36 (SF-36) is one of the most common generic scales used to measure quality of life and consisting of eight subscale and each scale is scored between 0 and 100. The higher scores showing the better health condition and it takes nearly 10 minutes to complete the health questionnaire [21]. Turkish validity and reliability have been obtained [22] and it is used in more than 200 diseases or conditions, including musculoskeletal diseases [23].

The Roland Morris Disability Questionnaire (RMDQ) is a 24-statement questionnaire that is widely used for patients with low back pain [24]. Each statement consists of Yes (1) or No (0) options and the total scores range from 0 to 24 points. It takes approximately 5 minute to complete [25]. The RMDQ has been shown to be valid and reliable in the Turkish population [8].

2.2 Translation and intercultural adaptation

In this study, the translation and intercultural adaptation processes were used following previously published guidelines [26, 27].

For forward translation of SBI and SFI, the indices were translated into Turkish according to conceptual translation of phrases by two translators, who know both Turkish and English. Afterwards, a common Turkish version was agreed by two translators. The Turkish version was, then translated back to English by other two translators, who were bilingual in Turkish and English. Finally, a review group, consisting of three pain medicine specialist, two physiatrists and one health care professional, made a synthesis of pre-final Turkish versions of the indices. The pre-final version was attempted on 10 LDH-induced radiculopathy patients with a 5-point Likert-type scale, and the Turkish version was detected that easily comprehended and it took approximately 1 minute to complete. Comprehensibility was excellent in the pilot study. No additional amendment was required.

2.3 Internal consistency (IC)

The IC [11] of the SBI and SFI was evaluated with Cronbach’s alpha ( $\alpha$ ). An $\alpha$ coefficient below 0.5 indicates a low validity, 0.5 to 0.7 moderate validity, 0.7 to 0.9 high validity, and greater than 0.9 excellent validity [28].

2.4 Test-retest reliability

Intra-class correlation coefficients were used for determined test retest reliability and a value of less than 0.5 was poor, between 0.5 and 0.75 was moderate, between 0.75 and 0.90 was good, and greater than 0.90 was considered excellent reliability [29].

2.5 Sample and procedures

This is a cross-sectional study conducted between November 2020 and March 2021. All patients were selected from the pain medicine clinic of our center Inclusion criteria were as follows: age between 18 and 65 years, pain and/or paresis under the knee and the presence of disc herniation confirmed with lumbar magnetic resonance imaging (MRI), and ability to understand and read Turkish. Exclusion criteria were pregnancy, tumor, infections, spine fracture, previous lumbar surgery and spinal stenosis.

The number of patients required per item in validation studies varies between 1.2 and 10. In some studies, the ideal number is considered 10 [30]. Therefore, we planned to recruit 10 patients per item in this study.

A total of 80 patients with LDH who presented with low back and leg pain were included in the study. Demographic data and back/leg NRS scores of all patients were recorded. The SF-36 and RMDQ, which are frequently used for low back pain to evaluate patients’ pain, quality of life, disability and also have Turkish validity and reliability, were preferred. The RMDQ, SF-36, SBI and SFI were filled by all patients. There was no significant difference between two days and two weeks for test-retest reliability [31]. Therefore, for retest, after 48 hours, all patients were called by phone to refill the SBI and SFI. The Turkish versions of the indices can be found in the Appendix.

2.6 Ethics

Ethical approval was obtained from the Institutional Ethics Committee of Marmara University (Ethics number: 09.2020.1206) and the study was conducted in accordance with the principles of the Declaration of Helsinki. Permission was obtained from Dr. Donald Patrick for the translation of SBI and SFI into Turkish. Written informed consent was obtained from all patients prior to enrolment

2.7 Statistical analysis

Statistical analysis was performed using the SPSS version 20.0 software (IBM Corp., Armonk, NY, USA). Descriptive analysis (frequency, mean and standard deviation) was used for the analysis of demographic data such as age, body mass index (BMI) and educational status. Variables were examined using the Shapiro-Wilk test, histograms and probability plots to determine the normality of the variables. Quantitative variables were expressed as mean $\pm$ standard deviation or median according to the characteristics of normality [32].

Concurrent validity was investigated by comparing the Spearman rank correlation coefficients of SBI and SFI with NRS for back/leg pain, subscales of SF-36 and RMDQ. A $p$ value of $<$ 0.05 was considered statistically significant.

3. Results

A total of 80 patients with LDH were included in the study. The mean age of the patients was 48.65 $\pm$ 13.88 years, the mean body mass index (BMI) was 28.78 $\pm$ 5.23 kg/m ${}^{2}$ and the mean duration of symptom was 21.35 $\pm$ 17.97 months. Half of the participants were females, were 64% employed and 41% had a high school education or university graduation (Table 1). The content validity ratio ranged between 0.67 and 1.00, and the mean content validity index score was found 0.92.

Table 1
Patients’ baseline demographic characteristics and clinical findings

Variables	Mean (standard deviation)
Female ${}^{*}$	42	(53)
Married ${}^{*}$	60	(75)
Employed ${}^{*}$	51	(64)
Education $>$ 12 year ${}^{*}$	33	(41)
BMI	28.78	(5.23)
Pain duration (months)	21.35	(17.97)
Age in years	48.65	(13.88)
Back NRS	6.32	(2.09)
Leg NRS	7.42	(1.86)
SBI ${}^{\text{a}}$	16.00	(5.64)
SFI ${}^{\text{a}}$	14.88	(6.27)
RMDQ	17.48	(5.40)
SF-36 Physical functioning	41.39	(25.16)
SF-36 Role physical	25.27	(12.3)
SF-36 Bodily pain	20.46	(13.78)
SF-36 General health	33.16	(20.60)
SF-36 Vitality	75.00	(7.68)
SF-36 Social functioning	44.62	(24.81)
SF-36 Role emotional	31.99	(21.42)
SF-36 Mental health	48.81	(19.47)
SBI ${}^{\text{b}}$	15.34	(5.18)
SFI ${}^{\text{b}}$	14.06	(5.75)

${}^{\text{a}}$ $=$ initial visit values, ${}^{\text{b}}$ $=$ values taken after 48 hours interval, ${}^{*}$ $=$ Mean (percent), BMI: Body Mass Index, NRS: Numeric Rating Scale, SBI $=$ Sciatica bothersomeness index, SFI $=$ Sciatica Frequency Index, RMDQ: Roland Morris Disability Questionnaire.

Table 2

Spearman’s correlation coefficient between the total scores of the SBI, SFI and other health status measurements at baseline

	SBI		SFI
SBI	1.	00	0.	84 ${}^{*}$
SFI	0.	84 ${}^{*}$	1.	00
Back pain (NRS)	0.	35 ${}^{*}$	0.	36 ${}^{*}$
Leg pain (NRS)	0.	68 ${}^{*}$	0.	64 ${}^{*}$
RMDQ	0.	51 ${}^{*}$	0.	57 ${}^{*}$
SF-36 Mental health	$-$ 0.	24 ${}^{*}$	$-$ 0.	25 ${}^{*}$
SF-36 Vitality	$-$ 0.	27 ${}^{*}$	$-$ 0.	22 ${}^{**}$
SF-36 Bodily pain	$-$ 0.	45 ${}^{*}$	$-$ 0.	49 ${}^{*}$
SF-36 General health	$-$ 0.	36 ${}^{*}$	$-$ 0.	41 ${}^{*}$
SF-36 Social functioning	$-$ 0.	21 ${}^{**}$	$-$ 0.	25 ${}^{*}$
SF-36 Physical functioning	$-$ 0.	42 ${}^{*}$	$-$ 0.	41 ${}^{*}$
SF-36 Role physical	$-$ 0.	38 ${}^{*}$	$-$ 0.	40 ${}^{*}$
SF-36 Role emotional	$-$ 0.	46 ${}^{*}$	$-$ 0.	48 ${}^{*}$

SBI: Sciatica Bothersomeness Index; SFI: Sciatica Frequency Index; NRS: Numeric Rating Scale; RMDQ: Roland Morris Disability Questionnaire; ${}^{*}$ Prespecified hypotheses confirmed; ${}^{**}$ Prespecified hypotheses not confirmed.

Table 2 shows the correlation between the SBI/SFI and leg NRS, back NRS, RMDQ and SF-36 subgroups. A strong positive correlation was found between the SBI and SFI ( $r=$ 0.84). A moderate positive correlation was found between the SBI and leg NRS ( $r=$ 0.68) and RMDQ ( $r=$ 0.51). There was a weak positive correlation between the SBI and back NRS ( $r=$ 0.35). A moderate positive correlation was found between the SFI and leg NRS ( $r=$ 0.64) and RMDQ ( $r=$ 0.57). There was a weak positive correlation between SFI and back NRS ( $r=$ 0.36). A weak negative correlation was found between the SFI/SBI and SF-36 subgroups ( $r=$ 0.21–0.49).

The IC of the SFI was high, as the Cronbach’s $\alpha$ value was 0.76. If one item was deleted each time, the Cronbach $\alpha$ varied between 0.65 and 0.76 (Table 3). The IC of the SBI was high 0.73 and if one item was deleted each time, the Cronbach $\alpha$ varied between 0.62 and 0.70 (Table 3).

Table 3

The SFI and SBI item’s mean scores, standard deviation and item-total correlation of individual items to whole-scale

No	Mean	Standard deviation	Cronbach’s alpha if item deleted
Sciatica Frequency Index (Cronbach’s alpha $=$ 0.76)
1	4.74	1.46	0.73
2	3.38	2.55	0.65
3	2.55	2.35	0.76
4	4.30	1.89	0.69
Sciatica Bothersomeness Index (Cronbach’s alpha $=$ 0.73)
1	5.05	1.36	0.69
2	3.81	2.08	0.62
3	2.53	2.22	0.70
4	4.56	1.83	0.63

No: Number of questions.

Table 4

Test and retest scores of the SBI and SFI, Intraclass Correlation (ICC) and change scores at 48 hours

	Mean (SD) of test (n: 80)	Mean (SD) of re-test (n: 80)	ICC with 95% CI	$P$ -value
Sciatica Frequency Index (0–24)	14.88 (6.27)	14.06 (5.75)	0.95 (0.92–0.97)	$P<$ 0.001
Sciatica Bothersomeness Index (0–24)	16.00 (5.64)	15.34 (5.18)	0.95 (0.92–0.97)	$P<$ 0.001

The test-retest reliability of the Turkish version of the SBI and SFI was 0.95 (95% CI: 0.92–0.97) and 0.95 (95% CI: 0.92–0.97) respectively, indicating excellent reliability (Table 4).

4. Discussion

Although there are many assessment scales for sciatica, SBI and SFI are an easy-to-understand and fast-applicable options that specifically assess the clinical effects of sciatica. In the present study, we translated the English version of the SBI and SFI, adapted them cross-culturally, and evaluated their psychometric properties according to the recommended guidelines [26, 33]. The Turkish version of SBI and SFI demonstrated adequate psychometric properties including construct validity, IC, and test-retest reliability.

In the literature, the minimum value for content validity need to be 0.80 [34]. In the current study, the mean content validity index score was found 0.92 and met the content validity criteria. The IC of the SBI/SFI was found to be high. In previous studies, IC was found to be moderate and high for both indices [13, 14].

In the current study, a strong positive correlation was found between the total scores of SBI and SFI, consistent with a previous study [12]. The SBI and SFI showed a moderate positive correlation with the leg NRS and a weak positive correlation between the back NRS. The reason of weak correlation between SBI/SFI and back pain may be due to the fact that three of the four questions measure radiating symptoms and only one questions measures back pain. Grøvle et al. and Shah and Soni also found that there was a moderate positive correlation between the SBI/SFI and leg Visual Analog Scale (VAS), while a weak positive correlation between the SBI/SFI and back VAS [12, 14].

According to Billis et al., a weak positive correlation was found between the RMDQ and SBI [13]. In another study, Grøvle et al. found a moderate positive correlation between the SBI/SFI and Maine Seattle Back Questionnaire which is shortened form of RMDQ [12]. In the present study, we found a moderate positive correlation between RMDQ and SBI/SFI. The moderate correlation between RMDQ and SBI/SFI can be attributed to the fact that the RMDQ only measures back pain symptoms while not measuring radicular symptoms.

In the Greek validity and reliability study of SBI, a weak negative correlation was found between SF-12 and SBI [13]. Shah and Soni found a strong negative correlation between role-physical and general health subgroups of SF-36 and SBI/SFI. However, they found a moderate negative correlation between all other SF-36 subgroups and SBI/SFI [14]. Grøvle et al. showed that there was a weak negative correlation between mental health, emotional role, general health and physical functioning of SF-36 subgroups and SBI/SFI [12]. Similar to the literature, in this study a weak negative correlation was found between SF-36 subgroups and SBI/SFI. The reason for the negative correlation between SF-36 and SBI/SFI is that higher scores in SF-36 indicate better functionality. Additionally, the SF-36 does not contain items that directly measure radicular symptoms and, therefore, may cause weak correlation with SBI/SFI.

The test-retest interval was chosen as 48 hours to eliminate time-related bias as in previous studies [13, 14]. Intra-class correlation coefficient values for SBI and SFI were 0.95 (0.92–0.97) and 0.95 (0.92–0.97), respectively indicating an excellent test-retest reliability. We believe that, with the indices being used in Turkish, sciatica patients would be easier to follow and further studies would be published. In this way, we assume that the indices would create a need for translation in other countries as well.

All participating in this study were selected from a single pain medicine clinic, which can be considered a limitation. As a result these findings may not be valid for primary care patients. Another limitation is that this study has a single-center design Despite these limitations, having high number of patients and examination of a specific patient group are the main strengths of this study.

5. Conclusion

The Turkish versions of the SFI/SBI are reliable and valid tools to assess bothersomeness and frequency in Turkish speaking patients with LDH-induced sciatica. Also, these tools can be useful for clinical practice and research purposes.

Footnotes

Acknowledgments

The authors thank Dr. Imran Kalkan, Dr. Gunay Yolcu and Selma Gocmen.

Conflict of interest

The authors declare they have no potential conflict of interest regarding the investigation, authorship, and/or publication of this article.

Funding

This study received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Appendix: Turkish version of the indices

Siyatik Sıklık Endeksi ve Siyatik Rahatsızlık Endeksi
İsim:<
Tarih:
	Hiç	Çok nadir	Bazen	Zamanın yarısı	Genellikle	Neredeyse Her zaman	Her zaman
Bacak ağrısı
Ayakta veya kasıkta uyuşma veya karıncalanma
Bacakta veya ayakta zayıflık
Otururken bel veya bacak ağrısı

Toplam skor: Siyatik Rahatsızlık Endeksi
	Rahatsıze dici değil			Bazen rahatsız edici			Aşırı rahatsız edici
	0	1	2	3	4	5	6
Bacak ağrısı
Ayakta veya kasıkta uyuşma veya karıncalanma
Bacakta veya ayakta zayıflık
Otururken bel veya bacak ağrısı
						Toplam skor:

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Reliability and validity of Turkish versions of Sciatica Bothersomeness and Sciatica Frequency Index

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Methods

2.1 Measures

2.2 Translation and intercultural adaptation

2.3 Internal consistency (IC)

2.4 Test-retest reliability

2.5 Sample and procedures

2.6 Ethics

2.7 Statistical analysis

3. Results

Table 1 Patients’ baseline demographic characteristics and clinical findings

5. Conclusion

Footnotes

Acknowledgments

Conflict of interest

Funding

Appendix: Turkish version of the indices

References

Table 1
Patients’ baseline demographic characteristics and clinical findings