Introduction
The Scoliosis Research Society (SRS) questionnaire is a well-establishedand validated 24-item survey that evaluates the different domains of health-related quality of life (HRQOL), including pain, individual self-image, activity level, physical function, and personal satisfactionin scoliosis patients. Since its development, the SRS has subsequently been modified to the current SRS-22 version.2,3 In both the United States and on a global scale, the SRS-22 has been repeatedly tested and regarded to be both a highly valid and reliable tool for assessing the spectrum of disease severityin spinal deformity and its treatment on affected adult and adolescent populations.4-15 The SRS 22 has been adapted to at least 19 different languages and/or cultures.4, 16,17 There is collective interest in developing SRS-22 normative baselines for different countries. Demographic factors have significant influence on the variability of the SRS-22.16-19 This has been done previouslyfor healthy adolescents in countries such as the US, Ghana, Japan, and China.15-20However, there remains a paucity of data for other countries that use the SRS-22; specifically, normative data is lacking in Europe and Asia, which are important for cross-cultural comparisons. The purpose of the study was to establish a normative baseline for the SRS-22 in India from a population of healthy adolescents without scoliosis. In addition, we aimed to describe the effect of demographic variableson the SRS-22. Finally, comparisons between the US, Ghana, and India were made from historical data.
Materials and Methods
This was a prospective study assessing SRS-22 data obtained from adolescents without scoliosis in India. Following local school board approval, 1200 adolescents without spinal deformity were asked to anonymously complete the questionnaire. The local review board did not require parental consent. Student participation was optional and responses were anonymous. All SRS-22 questions were included, with the exception of questions 21 and 22, which assessed postoperative satisfaction, and the SRS-22 domain Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. scores were calculated in a fashion that has been explained in past literature. Adolescents participating in the study were also provided with information about the SRS-22, study goals, confidentiality of response and further contact information.
Subjects: India
Subjects age 10 to 18 without extensive medical history or prior record of scoliosis were asked to anonymously complete the SRS-22 questionnaire and corresponding demographic questions. Participation was optional. A total of 1,019 SRS-22 questionnaires and demographic questions appendices were completed, giving an 85% response rate. Data was collected at a school in South India. A senior author and local school official distributed the SRS-22 and demographic questions to the adolescents during school hours.
Demographics
In addition to the SRS-22 questionnaire, participants also answered specific demographic questions to assist in examining cross-cultural variation (Figure 1). The demographic factors assessed were: age, gender, height, weight,and body mass index (BMI). Household income range was assessed: (in thousands of Indian rupees), less than 75, 75to 150, 150 to 250, 250 to 350, 350 to 625, 625 to 1000 (1 million), and greater than 1000. At the time of this study, the approximate exchange rate:1 US Dollar = 60 to 62 Rupees. Household status (single vs. dual parent income) was also recorded. In a previous study, household status indicated single versus dual parent in the home. However, divorce in Southeast Asia is uncommon,so the household status definition was modified in a culturally appropriate manner to single versus dual parent income.
Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Cross Cultural Comparison
From normative data gathered previously in the United States and Ghana, unmatched cross-cultural comparisons were made for the SRS-22 using an ANOVA test. The comparisons are meant to highlight the dramatic effect of cultural and demographic factors. While the population size and demographics differed between these groups, the methodology for data collection was virtually identical. In all cases,SRS-22 and demographic data was anonymously gathered from a local school after appropriate approval with the school board.
Statistics
Data was stored anonymously into a de-identified database without any patient identifiers. Mean and range for demographic quantitative values were calculated. Following a description of the demographic data of the healthy adolescents from India, a Pearson’s correlation between demographic data (age, gender, body mass index, household status, and income range) and clinical outcomes (SRS-22 domains [Activity, Image, Pain, Mental] and overall score) was completed (Table 2). A t-test was used to compare categorical demographic factors (gender, SRS-22 domains, and overall score). The mean and standard deviation for each SRS-22 domainand overall score for healthy adolescents from India, the US, and Ghana, which were collected in previous studies, weregathered (Table 3).16,17 Aone-way ANOVA performed between groups was then achieved with the understanding that the groups were unmatched for demographic variables and sample size.
Results
Descriptive statistics (Table 1)
1200 healthy adolescents were asked for their anonymous participation in the study. Of these, 1019 completed the SRS-22 and additional demographic questions (432F, 587M) for a response rate of 85%. All subjects completing the SRS-22 also completed the demographic questions. The healthy adolescent Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. profile was as follows: average age 14 (range 10-17) years, av erage height 157.1 (range 122-200) centimeters, average weight 46 (range 21-98) kilograms, with an average body mass index (BMI) of 18.5 (range 8.9-32.7). There were 640 single and 379 dual income families. Average income was between 75,000 to 150,000and 150,000 to 250,000 (income ranges 2 & 3 on Figure 1). The mean of each domain and overall SRS-22 questionnaire score for totalIndiahealthy adolescents were as follows: activity 3.9 ± 0.5, pain 4.3 ± 0.7, self image 3.9 ± 0.6, mental 3.8 ± 0.6, mean 4.0 ± 0.4 (Table 3).
Correlation Analysis (Table 2&3, Figure 2&3)
Small correlations were found between age, gender and BMI and individual SRS-22 domain scores. However, household status and income did not have a significant effect on the SRS-22 (Table 2). Specifically, older age was correlated with a worse self image score (r = -0.166, p< 0.0001, Figure 2). Male gender was also correlated with a lower pain score (more pain, r = -0.149, p<0.00), worse mental health (r = -0.109, p<0.001), and worse overall SRS-22 score (r=-0.110, p<0.001). The mean of the pain and mental health domains and overall SRS-22 score for females and males were as follows: pain 4.4 ± 0.6 (F) and 4.2 ± 0.7 (M), mental 3.8 ± 0.6 (F) and 3.7 ± 0.6 (M), mean 4.0 ± 0.4 (F) and 3.9 ±0.4 (M) (Table 3, Figure 3). Specifically, the magnitude of the difference between males and females was also compared with a t-test, showing a significant difference for mental health and overall SRS-22 scores. The small differences between mental health and mean SRS-22 between genders, however, are clinically below the minimally clinically important difference (MCID) quoted in studies 22,23 and are essentially equal (Table 3).
Cross Cultural Comparisons (Table 4)
There was a significant difference between Ghana, India, and USA in terms of the activity domain (p< 0.0001). Specifically, healthy adolescents in India had a lower activity score (3.9 ± 0.5) than Ghana (4.6 ± 0.5) or America (4.1 ± 0.5). In addition, healthy adolescents in America had a significantly lower Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. activity score than Ghana. For the image domain, adolescents in India (3.9 ± 0.6) scored worse than Ghana (4.2 ± 0.6) or the US (4.2 ± 0.7). However this statistical difference may not be clinically meaningful.23There were no image domain differences, however, between USA and Ghana. For mental health, healthy adolescents from Ghana scored worse (3.6 ± 0.6) than healthy adolescents from India (3.8 ± 0.6) or the United States (3.8 ±0.7). Of note, there was no significant image domain difference between India and the United States. For mean SRS-22 score, India had a minimally lower score (4.0 ± 0.4) than either Ghana (4.1 ± 0.4) or the United States (4.1 ± 0.5). As before, the differences in the mean SRS-22 score for US and Ghana were non-significant. In addition, pain domain scores for all countries were not significantly different. Lastly, statistical differences less than 0.2 in the pain domain are likely below the MCID. 23
Discussion
The SRS-22 is a short subjective self-assessment test that is utilized to evaluate the mental and physical effects of the adolescent idiopathic scoliosisdisease process. Haher et al. was the first to construct and evaluate the SRS-24 instrument as a tool to assess and discriminate amongadolescent idiopathic scoliosis (AIS) patients. This initial study was evaluated in 244 AIS patients but was limited to only 26 adolescents without scoliosis. In two subsequent studies, the SRS-22 was further refined to improve the internal consistency of the instrument but these studies also focused primarily on AIS patients.2,3In 2010, our group reported the first large normative dataset in the United States from a cohort of 450 persons. This study also reported the notable influence of age, gender, race, income and household status. 17Subsequently, Daubs et al. published an even larger baseline from over 3000 adolescents without scoliosis that mirrored the findings from the 2010 study. The large population baseline allowed for subgroup analysis based on age and gender as these were noted to influence SRS-22 score. In the adult population, Baldus et al. established a normative baseline from over 1200 adults without spinal deformity. However, these adults were not independently analyzed for the influence of demographics. Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Normative SRS-22 data also seems to vary with region. In 2014, the first SRS-22 normative dataset from West Africa was published helping to validate the use of the questionnaire in this region.16Overall, Ghanaian adolescents had a lower SRS-22 score compared to American counterparts when matched for age and gender.
This was especially true of AIS patients in Ghana compared to AIS patients in America. These studies support the notion that the SRS-22 is a snapshot of an individual’s physical and mental state at a specific time. The SRS-22 score seems to vary not only with the disease process, but also development during the adolescent period and demographic factors. The present study established the first SRS-22 normative baseline for adolescents in India. In addition, the influence of demographic factors – height, weight, gender, single vs. dual parent income, total family income were assessed. Lastly, normative SRS-22 scores from SE-Asia were compared with normative data from America and Ghana. We report that baseline SRS-22 scores from healthy adolescents without scoliosis in India are notably lower in all domains as compared to the United States.17,19 Age, gender, and BMI were demographics to have the greatest impact on the SRS-22 from the correlational analysis. Interestingly from age 12 to 15, there was a statistically significant decline in the body image domain score from 4.5 to 3.8 that may approach the MCID threshold (range 0.5 to 1.3). The body image domain has a higher MCID than pain, function, or mental health and the threshold cutoff for MCID is variable in the literature 22,23. However, the changes observed during this period of adolescence underscoresthe natural changes in body image that accompany maturity during adolescence. The potentially confounding effectdoes not have anything to do with spinal deformity. A similar pattern was reported in Americans as well.19 However, female adolescents without scoliosis in Asia had a more favorable pain score (less pain) compared to males. This is in contrast to the findings observed in the United States. In an un-matched comparison, healthy adolescents in SE-Asia had a statistically lower activity, image, and overall SRS-22 scores compared with WestAfrica and America.
Mental health, however, was still lowest in West Africa. While this cross-cultural comparison is historical in nature and susceptible to several types of bias, it does highlight the influence of cultural factors and the importance of Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. validating the SRS-22 in different regions.While the MCIDhas been shown to be less reliable for the activity domain22,23, Africa had the highest activity score (4.6 vs 4.1). In contrast, India had the lowest image domain score (3.9 vs 4.2). Wu et al. recently established the first normative dataset from 2000 adolescents without scoliosis in China. Unlike India, males in China had higher self-image and pain domain scores than females. Similar to other regions, however, age and gender had a significant affect on SRS-22 score. Functional activity scores improved in males with age, while they decreased in females from age 12 to 16. There has been a growing interest in utilizing the SRS-22 with special attention to cultural influences and race. Morse et al. recently reported the effect of culture and ethnicity among a large cohort (n=1800) of AIS patients. Although patients from India specifically were not included in this analysis, culture and ethnicity were found to influence all domains. Evaluating scoliosis patients abroad, Alanay etal. adapted a Turkish version of the SRS-22 with a 0.72-0.83 correlation coefficient. This followed with similar validation studies in numerous countries over the last 10 years namely: Japan,15,21 Canada,5,9 Greece,11 Germany,10 Persia,8 Thailand,6 and the Netherlands.4
Despite this international utilization, all of these studies excluded normal patients and focused primarily on AIS patients. In order for the SRS-22 to be useful in other countries, normative baselines for age, gender and other demographic factors should be established. These baselines allow clinicians to begin cross-cultural comparisons of clinical outcomes. Our study is limited to a single area of India and may be influenced by a language barrier, although English is considered a national language of India and is taught in all schools. Also, MCID calculations from previous studies are determined from operatively treated AIS patients. Therefore the MCID for patients without scoliosis remains unknown. In addition, the historical cross-cultural comparison is prone to bias. Statistical differences in patients without scoliosis may not translate to meaningful clinical differences in an AIS population. Our study has several strengths: (1) it is the first such study from India, (2) data was gathered from a large population of adolescents, (3) the influence of gender and age are clearly delineated, (4) and Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. finally, we begin to make cross cultural comparisons with previous studies. Future work should explore various regions in India and obtain additional data from AIS patients. Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
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