This cross-sectional, descriptive, observational quantitative study was carried out between January and April 2015 at college of medicine, King Saud University in Riyadh, Saudi Arabia. The study subjects were female medical students from 1
st, 2
nd, 3
rd, 4
th and 5
th year, which were at a total of 595 students (1
st:114, 2
nd:137, 3
rd:123, 4
th:123 and 5
th:97). The sample size was calculated by assuming a prevalence of BDD as 10%, with a precision of 3%, at 5% level of significance and assuming a 15% non-response, thus a total of 444 subjects were considered as the sample (
15). The 444 students were divided equally to five strata according to their academic year using the systemic random sampling technique. From every academic year, 89 students were sampled with a sampling interval of two.
Self-administered questionnaires with an informed consent were distributed to the randomly selected students in the college. The questionnaire consisted of four parts. The first part included socio-demographic information: age, year of enrollment in medical college, weight and height. The second part included a valid and reliable questionnaire, which was the “body image disturbance questionnaire” (BIDQ) adapted by Cash et al. (
16). All the questions were adapted from the original BIDQ without any modifications except for question two, which were added to assess the foci of concern (
7). Question 1 and questions 3 - 8 were the seven questions of the BIDQ, which constituted the scoring scale. The score was the mean of the seven items scaled from one to five. A score of > 3.0 was the cut-off for identifying BDD. The third part included a questionnaire about BDD symptomology. These symptoms vary from compulsive touching of the perceived defect, compulsive mirror checking, avoidance of looking into a mirror or being photographed, comparing the perceived defect with people around them or with people from magazines and television, and hiding or concealing the physical defect (
7). For more accurate results we added a question to exclude participants with already diagnosed Anorexia Nervosa and Bulimia. The fourth part included a valid and reliable questionnaire, which was the social interaction anxiety scale (SIAS), developed by Mattick and Clarke (
17). This questionnaire was used to assess prevalence, severity and treatment outcomes of social phobia and social anxiety disorders. It consisted of 20 questions in which responses were scored on a scale ranging from zero (not at all characteristic of me) to four (extremely characteristic of me). The score was the sum of all 20 items. A score of 43 or more indicated social anxiety, and a score of 34 or more indicated social phobia.
3.1. Reliability and Validity of the Three Instruments (BIDQ, BDD Symptomology & SIAS)
The internal consistency using Cronbach’s alpha had values of 0.840 for BIDQ (P < 0.001; 95% confidence interval (CI): 0.814 to 0.864), 0.786 for BDD symptomology (P < 0.001; 95% CI: 0.75 to 0.818) and 0.852 for SIAS (P < 0.001; 95% CI: 0.828 to 0.874). Factor analysis showed that all the items were correlated with other items (at least of 0.50) in each of these three instruments. The Kaiser-Meyer-Olkin measurement of sampling adequacy was 0.849, Bartlett’s test of sphericity was χ2 (21) = 972.24, P < 0.001 for BDIQ, 0.812, χ2 (15) = 725.46, P < 0.001 for BDD symptomology and 0.919, χ2 (190) = 2597.77, P < 0.001 for the SIAS instrument. All the three instrument sampling adequacy values were greater than the recommended value of 0.6. By using eigenvalue of > 1, the one factor extraction (of the seven items) for BIDQ explained 52.12% of total variance and factor loading had a range of 0.601 to 0.812. The one factor extraction (of the six items) for BDD symptomology explained about 51.86% of total variance and factor loading had a range of 0.504 to 0.826. The four factor extraction (of the 20 items) for SIAS explained about 56.41% of total variance and factor loading had range of 0.442 to 0.796. The analysis of our data indicated that the three instruments had good reliability and validity.