ECOS-16 was developed to evaluate the quality of life in postmenopausal patients with osteoporosis. It is a brief, straightforward, self-administered questionnaire containing 16 easy-to-score items, 4 of which are taken from OQLQ [6] and the remaining 12 taken from the Questionnaire of the QUALEFFO-41 [4]. The 16 items are further divided into four subscales: pain (5 items), physical functioning (5 items), illness-related fear (2 items), and psychosocial functioning (4 items). Each question related to these items has five response options, ranging from 1 to 5, where 5 represents the worst quality of life score [7]. ECOS-16 provides both subscale domain scores and an overall score.

The cross-cultural adaptation was performed based on guidelines including the following: (1) contact with ECOS-16 developers, (2) initial translations (forward translation from English into Persian), (3) synthesis, (4) backward translations, (5) expert team review, (6) test of the pre-final version, and (7) final version. Forward translation from English to Persian was independently completed by two bilingual translators, who were native Persian speakers and well conversant in English. One of the translators is a Neurosurgeon and the other is a full-time translator with no medical background and was not informed of our investigation. The two forward translators and other research team members discussed revision and modification of the questionnaire regarding language expressions and cultural differences. A provisional Persian version of ECOS-16 was then obtained. Then, two other professional translators translated this provisional version back into the English language. Finally, an expert committee comprising translators, researchers, and an outcome methodologist reviewed the translation and cultural adaptation processes. After a careful review and cultural adaptation, few changes were made, and the provisional Persian version of the questionnaire was created. To test the provisional version, patients were invited to complete the pre-final ECOS-16 for assessment, and their feedback was collected. The researchers met once more to make final adjustments in response to this feedback, and the final Iranian version of ECOS-16 was obtained.

Between January 2013 and April 2016, the final Iranian version of ECOS-16 was administered to a sample of consecutive patients with osteoporosis who presented to the neurosurgery clinics in two hospitals in Tehran, Iran. Diagnosis was based on World Health Organization criteria and was confirmed by a bone mineral density (BMD) test using dual energy X-Ray absorptiometry (DXA) of the lumbar spine and/or the hip. The DXA results were expressed as BMD (T-scores), and patients with T-scores ≤–2.5 were included [12]. Vertebral fractures were defined based on Genant's classification [13]. There were no restrictions on patient selection based on types of osteoporotic vertebral fracture, age, or other characteristics. A trained neurosurgery resident collected the data for this study over the course of one complete calendar year. Among the included patients with osteoporosis, those with at least one vertebral fracture underwent surgery and were included in surgery group, while those with no fractures did not undergo surgery and were considered as the control group. Patients who underwent standard surgical procedures [14] were assessed at two points in time: preoperative and postoperative (6-month follow-up). Surgery for patients included vertebroplasty and kyphoplasty. The indication for vertebroplasty or kyphoplasty was chronically painful vertebral compression fractures in patients failing 4–6 weeks of conservative therapy. Contraindications to these procedures included fractures with a disruption of the posterior vertebral wall, neurological deficit, or complete collapse of the vertebral body [15].

The Iranian version of the 36-item short-form health survey (SF-36) was also simultaneously completed. It includes 36 items in eight domains: physical functioning, social functioning, role limitations due to emotional problems, role limitations due to physical problems, vitality, mental health, bodily pain, and general health perception. The score for each subscale ranges from 0 to 100, with lower scores indicating worse conditions [16]. In this study bodily pain, physical functioning, mental health, and vitality were used for evaluation.

The Ethics Committee of the Shahid Beheshti University of Medical Sciences approved the study.

In total, 137 postmenopausal women with osteoporosis completed the questionnaire. The mean age of the patients was 58.6 (standard deviation, 7.1) years; most of them were married (67.9%) and had completed a primary or secondary education (70.1%). All the patients had an osteoporosis intensity score (T-score) ≤–2.5 and received bisphosphonate alendronate and calcitonin. They also received calcium and vitamin D3 as supplements. The characteristics of the patients are shown in Table 1.

The internal consistency of ECOS-16 measured using the Cronbach's alpha coefficient ranged from 0.82 to 0.84 at the preoperative assessment, indicating a satisfactory result. These results are shown in Table 2. Further analysis also indicated that the test-retest ICC value (95% confidence interval) was 0.85 (0.68–0.91) for the total score of ECOS-16, indicating a good reliability.

The validity of ECOS-16 was evaluated using item-scale correlations, criterion validity, and known-groups comparison (discriminant validity). The item-scale correlation matrix between each item and the three ECOS-16 subscales including pain, physical functioning, and mental function (fear of illness+psychosocial functioning) are shown in Table 3. All correlations between the items and its hypothesized scale showed satisfactory results, suggesting that the items had a substantial association with their own subscales. Pearson correlation coefficient exceeded the pre-established level (r≥0.40), ranging from 0.54 (Q4) to 0.71 (Q13). The criterion validity analysis showed significant correlations between all subscales in the ECOS-16 questionnaire and their corresponding subscales in SF-36 (p<0.001) (Table 4). It also exhibited good discriminate validity, with both subscale and overall scores differing between the categories of surgery and control groups (Table 5).

Responsiveness to change was evaluated using paired t-test. At all instances, ECOS-16 detected changes after intervention (surgery), indicating improvements in all subscales (Table 6). The ES and SRM totals were 0.85 and 0.93, respectively.