Prevalence of Sexual Dysfunction Among General Population of Iran: A Systematic Review

Sexual dysfunction is known to be of the most prevalent problems in general population estimated about 10% - 25% among males and 25% - 64% among females (1). Achieving a reliable estimation about the prevalence of sexual disorders is an essential step towards its prevention and treatment. So far, two review articles have been published about the prevalence of sexual dysfunction in Iran. A systematic review on the prevalence of sexual disorders among Iranian general population was published in 2007 (1). Insufficient number of published studies since then and diversity of findings have limited the outcomes. Another systematic review on the prevalence of sexual dysfunction in Iran is going to be published. In that review, articles related to the prevalence of sexual dysfunction in severe medical patients have been included but some important papers about general population have not been surveyed. Also, the diversity in findings was high (2).

Low quality and high diversity in methodology of prevalence studies on sexual disorders have been noted in other studies. A systematic review in 2002 on the prevalence of sexual disorders concluded that heterogeneity in methodology, study design, and case definitions made it difficult to determine a reliable overall estimate of sexual disorders (3). In 2006, a systematic review on female sexual disorders found only 11 out of 1248 related studies to meet defined standard inclusion criteria. Based on those 11 studies, it was reported that average sexual desire disorder, orgasmic disorder, arousal disorder, and sexual pain disorder in females were 64%, 35%, 31%, and 26%, respectively (4). Another review on male sexual disorders concluded that the most prevalent dysfunction in males was premature ejaculation (14% - 30%) followed by erectile dysfunction (10% - 20%) (5). A review that aimed to compare Asia with the rest of the world in terms of sexual disorder prevalence found large differences in the age of participants, definition of sexual disorder, study durations, and number of respondents (6).

Recently, research in Iran has shown a significant improvement both in quality and in quantity. Therefore, the authors decided to systematically review the recent conducted studies on the prevalence of sexual disorders in non-clinical population. If the quality and quantity of the data allowed, the authors would plan to perform a meta-analysis.

To find appropriate studies, 5 databases including PubMed, Scopus, Google scholar, IranMedex, and Scientific Information Database (SID) were searched. Moreover, hand searching of key journals introduced by Scopus were done including “Journal of Sexual Medicine”, “Iranian Journal of Reproductive Medicine”, and “International Journal of Impotence Research”. Eeventually, references cited by all the included studies were undertaken.

The key terms were: sexual dysfunction (disorder), hypoactive sexual desire disorder, low sexual desire disorder, frigidity, sexual arousal disorder, lubrication disorder, sexual pain disorder, dyspareunia, vaginismus, sexual satisfaction disorder, orgasmic disorder, anorgasmia, erectile dysfunction, impotency, premature ejaculation, and delayed ejaculation. Titles, abstracts, and MeSH term tags were used for all the key terms. The “Iran” key term was searched in titles, abstract, place of journal publication, and affiliation tags. All of the sexual dysfunction’s related key terms were combined with “OR”, and all of the combinations were combined with “AND” plus “Iran”. When searching the Persian databases, we used the exact Persian translation of the key words.

Two independent observers extracted the data according to a researcher-designed checklist. Qualitative measures including sampling method, randomization, validity and reliability of assessment tools, and methods of data collection were extracted from the reviewed articles and reports. Because of the limited number of published papers in this field, all the papers regardless of quality level were included.

The authors evaluated 128 published studies on the prevalence of sexual disorders in Iranian population. After reviewing abstracts and full texts, only 23 original studies were found to meet the selection criteria. The sample population included women in 20 studies, men in 2 studies, and both genders in one study. The sample size of the studies varied from 87 to 2626.

Most of the included papers were about female sexual dysfunction. 11.5% to 33% of all women in these studies were reported to have a job and the majority of women were housewives. Additionally, the majority of female participants did not have high education. Mean age of women were reported to be 24 to 34.04 years which shows that most of the included females in this review were at their golden time of reproductive age. Almost all women in these studies were married. Additionally, it should be mentioned that studies were from different areas of Iran. Generally speaking, it seems that the results of this review could represent middle class, sexually active females in Iran. All reviewed studies had cross-sectional design and none of them evaluated the lifelong prevalence of sexual disorders. Table 1 shows some characteristics of the studies on women.

The discrepancy between different articles and studies on the prevalence of sexual disorders in women seems to be relatively high. The reported ranges of the prevalence rates for total sexual disorders, sexual desire disorder, sexual arousal disorder, and lubrication disorder were estimated to be 19.2% to 77%, 15.4% to 65.8%, 9.8% to 88.3%, and 11.9% to 71.4%, respectively. In addition, the reported prevalence rates for pain disorder, female orgasmic disorder, and sexual dissatisfaction were estimated 9% to 95.9%, 10.5% to 76%, and 2.4% to 78.5%, respectively. Table 2 shows the prevalence of sexual disorders in Iranian women.

Three studies have evaluated sexual disorder among Iranian males. Safarinejad (28) conducted a cross-sectional study on a sample of 2674 men between 20 to 70 years of age. He has evaluated erectile dysfunction among sexual disorders. Rezakhaniha and Rezakhaniha conducted a study in a general urology clinic. Although no specific diseases for participants were reported, the findings could not be generalized to general population completely (29). Yekke and Goudarzi study (15) was conducted on 175 couples (175 males and 175 females). Among 175 male participants, most of them were between 30 and 40 years old; 43% had diploma, and 39% had a job. Table 3 displays characteristics of the studies and findings about sexual dysfunction in Iranian men.

When assessing the studies on their methodological quality, many pitfalls were emerged. For example, only 5 studies reported the participants’ response rate, 7 studies commented about the validity and 10 studies about the reliability of the scales. 9 studies used weak sampling methods like convenience or voluntary sampling. In 10 studies, researchers designed questionnaires that almost all of them were without enough psychometric descriptions. Generally speaking, the quality of most of the papers was not appropriate. Because of the diversity in the quality and quantity of the included studies, meta-analysis could not perform. Therefore, the authors have tried for subclass analysis. However, the diversity was still too high.

The present systematic review was performed to estimate the prevalence rate of sexual disorders in Iranian general populations (1).

The authors noted several interesting points which are mentioned below.

- Almost all subjects were married, probably because Iranian married participants feel more comfortable to talk about their sexual relationships. Another hypothesis might be that researchers were willing to respect social values.

- Women were much more evaluated about sexual disorders than men. This may be reflecting many years of cultural-male-superiority in Iran which seems to be moderating nowadays. It should also be noted that expressing sexual problems can be very distressful and tough for Iranian men due to a wrong myth that says: “a man without proper sexual performance is not really a man”. Therefore, it is assumed that researchers might be more comfortable about studying women’s sexual issue.

- The descriptive characteristics of female samples on the prevalence of sexual disorders have been similar among different studies. However, the reported rates varied quite obviously, which might be also related to the different sample sizes, geographical and cultural differences, and the nature of sexual disorders especially among females.

- In most studies, systemic view to the couples did not exist. In the systemic view, sexual problems belong to the couples instead of one partner. Assessing the sexual function while assuming couples as a unit will reveal important aspects of the problems.

- In spite of recently growing numbers of studies regarding the prevalence of sexual disorders, quality of most research studies is not satisfactory. Iranian studies did not address the characteristics of non-responding groups. Furthermore, different questionnaires were used in different studies leading to more difficult comparison of the results. Problems that were observed in these studies include lack of information on duration of assessment or participants’ response rates, not mentioning validity and reliability of questionnaires, and not utilizing appropriate sampling methods. Heterogeneity in the sampling methods has made the comparisons of the results more difficult.

- Prevalence rates of sexual disorders presented in our study are in a wide range.

Looking at studies in other regions of the world shows that the diversity in reported prevalence of sexual disorders is also notable. Erectile dysfunction was estimated from 15% in 40 - 49 year old males to 71% in 70 - 79 year-old males in Japan (30) and from 7% in 40 - 49 years to 49% in 60 - 70 years of age in Thailand (31). The prevalence rate of erectile dysfunction was lower in USA (from 1% in 40 - 49 years to 44% in 70 - 79 years) (32). A cross-sectional study that compared the prevalence of erectile dysfunction among 40 to 70 year-old males in 4 countries reported different rates: Brazil 15.5%, Italy 17.2%, Japan 34.5%, and Malaysia 22.4% (33). The prevalence rate of premature ejaculation was reported 12-29.7% in different parts of Asia (34). The diversity in reported prevalence of female sexual disorders was also high. For instance, the prevalence rate of female desire disorder was estimated to be 10 to 55% across different studies (5, 35-37). The prevalence of arousal and lubrication problems was estimated to be 8 to 40.9% (36). Similarly, the prevalence rate of female orgasmic disorder was reported to be 16.9 to 42.7% (5, 6, 37, 38), and some degrees of orgasmic disorder had prevalence rate up to 80% (39). The prevalence of pain disorders including dyspareunia was noted to be from 1 to 42.9% in different reports around the world (39).

The present review was done when DSM-IV-TR and ICD-10 were the standards of diagnosis. It should be noted that DSM-5 has been available since mid-2013 (40). In DSM-5, the “sexual aversion disorder” has been excluded from the list of diagnosis. Our study could not evaluate the prevalence of “sexual aversion disorder” due to scarce data in the literature. Additionally, in DSM-5, female desire and arousal dysfunctions have been merged and considered under the category of “female sexual Interest/Arousal disorder”. Both spontaneous and responsive desires are addressed in DSM-5. Moreover, vaginismus and dyspareunia are noted under the category of “Genito-pelvic Pain/Penetration disorder” in DSM-5. These merges were probably done because of difficulties in distinguishing the two primary diagnoses. Considering the heterogeneity of the prevalence rates in Table 2 the changes in DSM-5 diagnosis seem to be reasonable (40).

The present study encountered some limitations that are mentioned as follows. Due to the limitation of the local library facilities as well as difficulty and complexity of hand searching, the authors were not able to review grey literatures. Additionally, because of the diversity in the quality and quantity of the findings, a meta-analysis was not done.

Generally speaking, several factors including duration of assessment in cross-sectional studies, age of samples, target population, method of sampling as well as types of scales used for assessing patients, and the culture and education of selected samples would directly affect the reported prevalence rates. At least some part of the diversity noticed in evaluating the prevalence rates might be due to the methodological diversity.