Received: 29 March 2015 /Revised: 22 May 2015 /Accepted: 29 June 2015 /Published online: 21 July 2015 # Springer-Verlag Berlin Heidelberg 2015

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1 Sleep Breath (2016) 20: DOI /s ORIGINAL ARTICLE Translation, cultural adaptation, and validation of the Sleep Apnea Quality of Life Index (SAQLI) in Persian-speaking patients with obstructive sleep apnea Sara Rahavi-Ezabadi 1 & Amin Amali 2 & Khosro Sadeghniiat-Haghighi 3 & Ali Montazeri 4 & Saharnaz Nedjat 5 Received: 29 March 2015 /Revised: 22 May 2015 /Accepted: 29 June 2015 /Published online: 21 July 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Purpose The aim of this study was the translation, crosscultural adaptation, and validation of the Sleep Apnea Quality of Life Index (SAQLI) in Persian-speaking patients with obstructive sleep apnea (OSA). Methods Ninety-six patients with OSA completed a series of questionnaires including SAQLI, Epworth Sleepiness Scale (ESS),10-item Functional Outcomes of Sleep Questionnaire (FOSQ-10), and Medical Outcome Survey Short form 12 (SF- 12) for assessment of reliability, validity, and responsiveness of Persian version of SAQLI. Results The Persian version of SAQLI had a very good internal consistency and also demonstrated good test-retest reliability. Concurrent validity was confirmed by significant correlations with ESS, FOSQ-10 and SF-12 subscale scores. Comparison of SAQLI scores in groups of patients categorized by ESS showed the high discriminative power of this instrument. However, there was no significant difference in the SAQLI scores of patients with mild, moderate, and severe * Amin Amali a_amali@sina.tums.ac.ir Tehran University of Medical Sciences, Tehran, Iran Occupational Sleep Research Center, Otorhinolaryngology Head and Neck Surgery Department, Imam Khomeini Educational Complex Hospital, Valiasr Hospital, Tehran University of Medical Sciences, Tehran, Iran Occupational Sleep Research Center, Tehran University of Medical Sciences, Tehran, Iran Health Metrics Research Center, Iranian Institute for Health Sciences Research, ACECR, Tehran, Iran Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran sleep apnea. The results of sensitivity to change verified that the SAQLI was able to detect changes after continuous positive airway pressure (CPAP) treatment. Conclusion The findings of this study indicate that the Persian version of SAQLI is a reliable, valid, and responsive measure for evaluation of quality of life in patients with OSA. Keywords Translation. Validity. Reliability. Sleep Apnea Quality of Life Index. Persian version Introduction Obstructive sleep apnea (OSA) is a common disorder caused by complete or partial airway obstruction during sleep. OSA affects 4 % of men and 2 % of women aged more than 50 years. Common clinical presentations of OSA are loud snoring, snorting, choking and gasping during sleep, intermittent awakening, disrupted sleep, and excessive daytime sleepiness. Patients usually are not aware of nighttime symptoms until the progression of the disorder and appearance of daytime symptoms including excessive daytime sleepiness, chronic fatigue, morning headache, sore throat or dry mouth upon awakening, irritability, forgetfulness, and difficulty in concentration [1 4]. Sleep disruption and recurrent hypoxemia lead to cardiovascular sequelae, including systemic hypertension, coronary heart disease, heart failure, cardiac arrhythmias, pulmonary hypertension, and stroke. OSA is also associated with neurocognitive impairments, including impaired vigilance, deficit in executive functioning, impaired fine motor coordination, and depression. The prevalence of asymptomatic OSA in middle-aged population is % [5]. Weight gain, aging, and menopause are the most important risk factors [6]. OSA is now a major

2 524 Sleep Breath (2016) 20: public health issue considering its high prevalence as well as detrimental effects on physical, social, and mental functions; therefore, valid and responsive measures are required to assess the burden of OSA and treatment effectiveness. Disease-specific questionnaires such as Sleep Apnea Quality of Life Index (SAQLI), Functional Outcomes of Sleep Questionnaire (FOSQ), and Quebec Sleep Questionnaire (QSQ) are more likely to detect changes in quality of life in comparison with generic health-related quality of life (HRQOL) measures [7 9]. The SAQLI is a comprehensive measure designed to measure quality of life in patients with sleep apnea. The SAQLI has been validated in many languages [10 13]. Persian is widely spoken in Middle East, parts of Central and South Asia. The aim of this study was to examine the psychometric properties of Persian version of SAQLI. Methods Instrument The SAQLI was designed as a disease-specific HRQOL measure by Flemons and Reimer in The first 35 questions measure daily functioning, social interactions, emotional functioning, and symptoms. The fifth domain captures the potential negative consequences of the treatment. The symptoms and treatment-related symptom domains are individualized, and patients are asked to select the five most important symptoms they have experienced during the last 4 weeks. Questions are equally weighted, and each item is scored on a seven-point Likert scale, 1=greatest impairment to 7=least impairment. The SAQLI total and each domain score have a potential range from 1 to 7. Higher scores indicate better quality of life [14 16]. Translation After getting the permission for translation and the use of SAQLI from the copyright holder, the standard forwardbackward method was followed [17]. The original English version was first translated into Persian independently by two native Persian speakers (an otorhinolaryngologist specialized in management of OSA and a professional translator). A panel consisting of these two translators and one bilingual author (A.A) critically reviewed the translations to form the first draft of Persian version of SAQLI. Two other bilingual speakers who did not know the original questionnaire back translated this draft into English. The discrepancies between the original version, forward translation, and the back translation were analyzed by the panel (consisting of all five). Semantic, idiomatic, experiential, and conceptual equivalences were discussed, and pre-final version of questionnaire was developed. In next step, four content experts (otorhinolaryngologists and pulmonologists expert in OSA management), five lay experts, and one methodologist completed the questionnaire. Then, pretesting results were assessed and reconciled to produce the final Persian version of SAQLI. Study sample Ninety-six consecutive adult ( 18) patients with an apnea hypopnea index (AHI) of 5 were recruited for the study from August 2013 to September 2014 from patients, in whom OSA was clinically suspected, referring to Baharloo Sleep Center for overnight polysomnography (PSG). Patients with sleep disorders other than OSA were not included in the study. Any patients who had severe co-morbidities such as psychiatric impairment (e.g., depressive disorder, anxiety disorder, bipolar mood disorder, and dementia), chronic alcoholism, opium use, unstable cardiac vascular disease, chronic pulmonary disease, abnormal thyroid function, and cancer were not included in the study. Full ethical approval was granted by the research ethics committee of Tehran University of medical sciences. All patients were asked to complete a series of questionnaires including SAQLI, Medical Outcome Survey Short form 12 (SF-12), 10-item Functional Outcomes of Sleep Questionnaire (FOSQ-10), and Epworth Sleepiness Scale (ESS). Table 1 Demographic characteristics of patients (N=96) Mean (SD) Age (years), mean (SD) 46.3 (10.4) Sex, male (%) 72.9 % Marital status, married (%) 82.2 % BMI (kg m 2 ), mean (SD) (5.2) AHI (events h 1 ), mean (SD) 38.3 (21.7) ESS, mean (SD) 13.1 (5.7) FOSQ-10, mean (SD) (3.11) SF-12 Physical functioning, mean (SD) 74 (27.11) Role limits-physical, mean (SD) ) Bodily pain, mean (SD) 78.6 (21.21) General health perception, mean (SD) ) Vitality, mean (SD) 45.6 (28.29) Social functioning, mean (SD) ) Role limits-emotional, mean (SD) 62.5 (36.9) Mental health, mean (SD) 71.1 (20.14) BMI body mass index, AHI apnea hypopnea index, ESS Epworth Sleepiness Scale, FOSQ Functional Outcomes of Sleep Questionnaire

3 Sleep Breath (2016) 20: Table 2 The Cronbach s alpha values of SAQLI (N=96) Mean SD % Floor % ceiling Cronbach s alpha,ifitemdeleted Daily functioning Social interactions Emotional functioning symptoms Total Additional measures Polysomnography PSG is an objective test that assesses several physiologic variables during sleep including pulse oximetry, electroencephalogram, an electro-oculogram, nasal and oral air flow measurements, chest wall movements, electromyogram, and electrocardiogram. All patients underwent a full standard PSG. American Academy of Sleep Medicine (AASM) guideline was used for analyzing the tests [18]. A respiratory event was scored as hypopnea when the peak signal excursions drop by 90 % of pre-event baseline, for 10 s. Hypopnea was scored when the peak signal excursions drop by 30 % of pre-event baseline, for 10 s in association with 3 % oxygen desaturation from pre-event baseline or an arousal. AHI obtained by dividing sum of apnea and hypopnea by hours of sleep. Using the AHI, OSA is classified as mild (5 14), moderate (15 29), or severe ( 30) [19]. Medical Outcome Survey Short form 12 The SF-12 is a generic questionnaire that measures eight dimensions of health: physical functioning, role limitation due to physical problems, role limitation due to emotional problems, social functioning, mental health, vitality, bodily pain, and general health perception [20, 21]. Epworth Sleepiness Scale The ESS is an eight-item questionnaire to measure daytime sleepiness. Questionnaire has a four-point Likert response format (0 3), and the score ranges from 0 to 24 with higher scores indicating greater daytime sleepiness. ESS score >10 indicates pathologic sleepiness [22, 23]. Functional Outcome of Sleep Questionnaire The 10-item FOSQ is a disease-specific questionnaire designed to assess the impact of excessive sleepiness on daily activities. Items rated on a scale of 1 4. The total score ranges from 5 to 20 with higher scores indicating better functional status. Analysis Reliability Reliability of SAQLI was assessed by internal consistency and test-retest analysis. Internal consistency was determined Table 3 Correlation coefficients of SAQLI domains with ESS, FOSQ, and SF-12 domains (N=96) Daily functioning Social interactions Emotional functioning Symptoms Total ESS 0.23 a 0.21 a 0.1 a 0.27 a 0.21 a FOSQ 0.37 b 0.32 a 0.31 a 0.24 a 0.43 b SF-12 Physical functioning 0.43 b 0.27 b 0.31 b 0.24 a 0.53 b Role limits-physical 0.57 b 0.32 b 0.37 b 0.41 b 0.44 b Bodily pain 0.21 b 0.15 b 0.24 b 0.33 b 0.26 b General health perception 0.30 b 0.36 b 0.39 b 0.23 a 0.39 b Vitality 0.55 b 0.31 b 0.35 b 0.46 b 0.51 b Social functioning 0.39 b 0.56 b 0.43 b 0.26 a 0.51 b Role limits-emotional 0.32 b 0.29 a 0.39 b 0.36 b 0.49 b Mental health 0.31 b 0.47 b 0.61 b 0.23 b 0.59 b a <0.05 <0.01

4 526 Sleep Breath (2016) 20: Table 4 Mean SAQLI scores by ESS and AHI subgroups (N=96) ESS groups AHI groups ESS 10 N=21 ESS>10 N=75 P value 5 AHI<15 N=25 15 AHI<30 N=27 30 AHI N=44 P value Mean SD Mean SD Mean SD Mean SD Mean SD Daily functioning Social interactions Emotional functioning Symptoms Total using Cronbach s alpha coefficient. Test-retest analysis was tested after 2 weeks on a subsample of 20 subjects who did not receive any treatment. It was calculated using intraclass coefficient. Validity Concurrent validity was tested by correlations of SAQLI domains with ESS, FOSQ-10 total score, and SF-12 domains. Discriminant validity was analyzed by comparing different groups of patients categorized by ESS (normal: 10, excessive daytime sleepiness: >10) and AHI (mild: 5 14, moderate: 15 29, severe: 30). Responsiveness to change Responsiveness of SAQLI was analyzed after 3 months of continuous positive airway pressure (CPAP) treatment among 20 patients who had good adherence to CPAP and the SAQLI scores before and after treatment were compared. Statistical analysis Internal consistency was assessed using Cronbach s alpha coefficient. Alpha values 0.7 considered satisfactory [24]. Testretest reliability was assessed using intraclass coefficient (ICC). t test analysis and ANOVA tests were performed to examine how well the SAQLI could discriminate between groups of patients categorized by ESS and AHI. Concurrent validity was assessed by Pearson s correlation coefficient. Correlation coefficient power was categorized as poor (0 0.20), fair ( ), moderate ( ), good ( ), and very good (0.81 1). Responsiveness of SAQLI was assessed by paired t test. A P value <0.05 was considered statistically significant. All statistical analyses were performed using SPSS, version 18, SPSS Institute, Chicago, IL, USA. Results The mean age of the patients was 46.3±10.4. Seventy patients (72.9 %) were male. Seventy-nine patients (82.2 %) were married. Mean AHI was 38.3±21.7 h 1, and the mean body mass index was 29.06±5.2 kg m 2. Demographic characteristics of patients and mean score of ESS, FOSQ-10, and SF-12 are illustrated in Table 1. The Cronbach s alpha coefficient of internal consistency for the SAQLI total score was It was ranged from 0.79 to 0.84 for all domains (Table 2). The test-retest reliability investigated by ICC of all the four domains and the SAQLI total scores were the following: daily functioning 0.86, social interactions 0.89, emotional functioning 0.78, symptoms 0.64, and SAQLI total Table 5 Baseline and posttreatment scores of SAQLI (N=20) Baseline SD Posttreatment SD P value Daily functioning Social interactions Emotional functioning Symptoms <0.001 Treatment-related symptoms (recoded) Total <0.001

5 Sleep Breath (2016) 20: The correlations of SAQLI domains with ESS, FOSQ-10, and SF-12 domains are shown in Table 3. There were significant negative fair correlations between the SAQLI domains and ESS. The SAQLI total score showed moderate significant correlation with FOSQ-10. There were also fair but significant correlations between the SAQLI domains and FOSQ-10. The daily functioning domain of SAQLI had moderate significant correlations with role limits-physical (r=0.57), vitality (r=0.55), and physical functioning domains of SF-12 (r= 0.43). The social interactions domain of SAQLI had moderate significant correlations with social functioning (r=0.56) and mental health domains of SF-12 (r=0.47), emotional functioning domain of SAQLI with mental health (r=0.61) and social functioning domains of SF-12 (r=0.43), and symptoms domains of SAQLI with vitality (r=0.46) and role limitsphysical domains of SF-12 (r=0.41). The SAQLI total score also showed moderate significant correlations with physical functioning, vitality, role limits-physical, social functioning, and role limits-emotional and mental health domains of SF- 12. The SAQLI scores of patients grouped by AHI and ESS are summarized in Table 4. We found significantly lower scores in all domains of SAQLI in patients with higher sleepiness scores (ESS >10), but we did not find any statistically significant difference in the SAQLI scores among patients with mild, moderate, and severe OSA as classified by AHI. Changes in the SAQLI scores after CPAP treatment are shown in Table 5. The SAQLI scores significantly improved after 3-month CPAP treatment. The means of SAQLI total score before and after 3-month CPAP therapy were 4.55 and 5.66, respectively (P value<0.001). Discussion The SAQLI is a specific questionnaire which evaluates the areas of quality of life impaired by OSA. In this study, the SAQLI was translated, culturally adopted, and validated for Persian-speaking patients with OSA. Translation of the questionnaire was based on the standard forward-backward translation method. Patients answered the Persian version of SAQL I without difficulties. According to the results, the Persian version of SAQLI had an acceptable internal consistency and also demonstrated good test-retest reliability. Similar findings were obtained in the original English version of SAQLI (Cronbach s α= , ICC= ) [11]. When investigating concurrent validity, the highest correlations were found between comparable domains of SAQLI and SF-12. The daily functioning domain of SAQLI had the highest correlation with role limits-physical domain of SF-12, the social interactions domain of SAQLI with social functioning domain of SF-12, the emotional functioning domain with mental health, and the symptoms domain with vitality. The results of this study showed significant negative fair correlations between the SAQLI domains and ESS. There were also fair significant correlations between the SAQLI domains and FOSQ-10. These findings were relatively compatible with previous Chinese and Spanish reports [12, 14]. Comparison of SAQLI scores in groups of patients categorized by ESS showed the high discriminative power of this instrument. However, there was no significant difference in the SAQLI scores of patients with mild, moderate, and severe sleep apnea. Similar results were also reported in studied performed by Flemons et al., Lacasse et al., and Mok et al. [10 12]. The results of sensitivity to change verified that the SAQLI was able to detect changes after CPAP treatment. Similar results were also established in English, French, Spanish, and Chinese versions. The limitation of this study bears mention that we did not explore the factor structures of SAQLI. 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