Journal Logo

Research Article: Systematic Review and Meta-Analysis

A PRISMA systematic review and meta-analysis on Chlamydia trachomatis infections in Iranian women (1986–2015)

Roshani, Daem PhDa; Ramazanzadeh, Rashid PhDb,c; Farhadifar, Fariba MDa,d; Ahmadi, Amjad MScb,c,*; Derakhshan, Safoura PhDe; Rouhi, Samaneh PhD Studentb,f; Zarea, Shamsi MDd; Zandvakili, Farnaz MDd

Section Editor(s): Bakir., Mehmet

Author Information
doi: 10.1097/MD.0000000000010335
  • Open


1 Introduction

Sexually transmitted diseases (STDs) are the most common infectious diseases in the community and cause a financial burden on patients and communities. The World Health Organization estimates that there are 330 million new cases of STDs, most of these are in developing countries, each year. The causes of STDs are bacteria, viruses, fungi, and protozoa. STDs are a major threat to the health of human society.[1,2] These diseases are epidemically unrevealed, which is why early diagnosis is of great importance for their control.[2]Chlamydia trachomatis (CT) is a gram-negative bacterium with a diameter of 0.2 to 1.4 mm. This bacterium is an intracellular parasite for humans and animals that tend to proliferate in epithelial cells.[3,4] This is the most common bacterial infection that can be transmitted via sexual contact.[5] Complications from infection in women include infertility, ectopic pregnancy, vaginal discharge, dysuria, lower abdominal pain, pain during intercourse, and pelvic inflammation; and in men, it causes epididymis.[1,6] Infections in infants include pneumonia and conjunctivitis. Pregnant women who are infected with CT and diagnosed in time are typically treated between weeks 16 to 29.[7,8] Given the importance of different CT infections in women, the identification of this bacterium using an appropriate method in the population and obtaining a statistical result and general overview for prevention, and control and treatment are necessary. This study is interested in the frequency of CT infection among Iranian women using a systemic review.

2 Materials and methods

2.1 Data source

The research was approved by the scientific and ethical review committee at the Kurdistan University of Medical Sciences and the ethical code IR.MUK.REC1394.21. Also, in this study, patients were not directly examined and considered, only related articles were reviewed that were related with our aim and scope, so patient consent was not explicitly given. This study was done according to PRISMA guidelines.[9] Literature searches were applied using the following keywords

CT in women; CT and Iranian women; CT and infection in Iran; CT and pregnancy in Iran; CT and preterm delivery in Iran; CT and preterm labor in Iran; CT and preterm birth in Iran; CT and premature delivery in Iran; CT and prematurity in Iran; CT and premature child birth in Iran; CT and fertility in Iran; CT and infertility in Iran; and CT and abortion in Iran. The search was done using the medical literature published in databases including Google Scholar, PubMed, ISI Web of Science, Biological abs, Iranmedex, SID, and Scopus from 1986 to 2015. The initial literature search showed studies based on the guidelines. In the first search, 40 studies that were published between 1986 and 2015 were selected. Publication bias was checked using the Begg test. To reduce the possibility of selection bias in this study, criteria were clearly defined with the studies and data collection in each study was done by 2 researchers independently with the final list chosen by consensus. Information checklists for the papers consist of the following: first author's last name, year of publication, sample size, study period, method, the type of study, and place of study (Table 1).

Table 1
Table 1:
Data were extracted from published documents about publication year, place of study, method, sample type, sample size, and prevalence of Chlamydia trachomatis infections among Iranian women.

2.2 Study selection

Inclusion criteria were research articles with full text and articles with abstracts in English. Excluded studies were review articles, congress abstracts, studies in languages other than English, and studies with unclear data (Fig. 1).

Figure 1
Figure 1:
PRISMA flow diagram: Study selection process.

2.3 Data extraction

A total of 40 Iranian studies were chosen for analysis. Prevalence and the 95% confidence interval (CI) were calculated. The variance of each study was calculated using binomial distribution. Studies were combined based on sample sizes and the variances of samples. Due to the heterogeneity in the studies, meta-analysis with the random-effect model was applied to combine the prevalence among studies and to assess heterogeneity. The Cochrane Q test and I2 statistics were used. A P value <.05 was considered a significant heterogeneity test. The Freeman–Tukey double arcsine transformation was used to stabilize variances and a Forest plot was performed. Depending on the analyzed data, to examine publication bias, a Begg plot was used. Stratified analysis was subsequently performed with respect to sample types, methods, and regions. Statistical analysis was performed using the statistical software package Meta in R3 and STATA 12.

3 Results

3.1 CT infection in Iranian women based on the sample types

The data for 4 groups were analyzed for sample type and the lowest rate for CT samples was in the blood 9.5% (95% CI: 8.5–10) and the highest prevalence rate for CT samples was in urine 16.1% (95% CI: 14.8–17.4) (Table 2). As for heterogeneity, I2 = 96.5% (95% CI: 94.4–97.6); heterogeneity chi-squared test = 86.81 with 3 degrees of freedom and a P value <.0001; and moment-based estimates of between-study variance = 0.009, Kendall tau = −0.33, and P = .33 (Fig. 2).

Table 2
Table 2:
Proportion of Chlamydia trachomatis infection with 95% confidence interval in Iranian women based on the samples.
Figure 2
Figure 2:
Forest plot of proportion of Chlamydia trachomatis infection with 95% confidence interval in Iranian women based on the samples (fixed and random effects).

3.2 CT infection in Iranian women based on the method

The data for 3 groups were analyzed for method. The lowest rate of CT samples was for serology 8.7% (95% CI: 8.08–9.4) and the highest prevalence rate of CT samples was for culture 65.6% (95% CI: 62.4–68.7). The heterogeneity, I2 = 99.9% (95% CI: 99.8–99.9), heterogeneity chi-squared test = 1334.51 with 2 degrees of freedom, and P value <.00, and moment-based estimate of between-study variance = 0.181.

3.3 CT infection in Iranian women-based different parts of Iran

The data for 4 area were analyzed (North, South, East, and West), the lowest rate of CT prevalence rate was in southern Iran 8.8% (95% CI: 7.6–10.07) and the highest CT prevalence rate was in eastern Iran 59.03% (95% CI: 56–62.01). Regarding heterogeneity, I2 = 99.7% (95% CI: 99.7–99.8), heterogeneity chi-squared test = 1198.73 with 3 degrees of freedom and P value <.0001, and moment-based estimate of between-study variance = 0.171, Kendall tau = 1, and P value = .08.

3.4 Publication bias

Begg funnel plot was used to evaluate publication bias the included studies. The appearance of the shape of funnel plot did not show any evidence of publication bias among included studies (Fig. 3).

Figure 3
Figure 3:
Funnel plot detecting biases in the identification and selection of studies.

4 Discussion

CT is a bacterial infection of the genital tract affecting men and women. During pregnancy, chlamydial genital infection increases the risk of spontaneous abortion, premature delivery, and ectopic pregnancy. Infertility is a complication of these infections.[1] In this study, we performed a systemic review and meta-analysis on the frequency of CT infections among Iranian women in different regions of Iran. The results showed that from 1986 to 2015, the lowest rate of prevalence was in 2010 to 2011 (3.9%) and the highest prevalence rate was in 2009 (69.39%) in northern Iran. The fixed-effects model that was used for different parts of Iran (North, South, East, and West) had a pooled proportion = 0.13 (95% CI = 0.12–0.14) and when used on the samples (cervical, vaginal, urine, and blood) it had a pooled proportion = 0.14 (95% CI = 0.12–0.14). In a systemic review study conducted by Lewis et al in Australia, the pooled prevalence estimates of CT infections for indigenous women under 25 years was reported to be 22.1% (95% CI: 19.0–25.3).[50] In another systematic review by Adams et al on the female CT infections, prevalence was 8.1% (95% CI: 6.5–9.9).[51] In a systemic review study by Watson et al screening tests for CT performed, the pooled sensitivities for ligase chain reaction, polymerase chain reaction (PCR), gene probe, and enzyme immunoassay (EIA) on urine were 96.5%, 85.6%, 92%, and 38%, respectively; while on cervical swabs, the corresponding sensitivities of PCR, gene probe, and EIA were 88.6%, 84%, and 65%, respectively. Meta-analysis demonstrated that DNA amplification techniques are the best for urine and swabs in populations with a low prevalence.[52] In another systemic review study by Robert et al for noninvasive testing for CT performed, pooled study sensitivities for the PCR, transcription mediated amplification, and strand displacement amplification assays were 83.3%, 92.5%, and 79.9%, respectively, for CT infections in women, so that nucleic acid amplification tests for CT infections in urine samples are nearly identical to those obtained on samples collected directly from the cervix or urethra.[53] The results of our study agree with other review studies that most studies in Iran are due to sensitive tests based on molecular methods used for the detection of genital CT infections and less invasive because of urine sampling, because this method is used more for sampling. Also, the reason for the difference in the prevalence of CT infection in different regions is probably due to the socioeconomic situation of the family, health status, and the difference in population distribution in each region, which leads to the lack of proper referral of women to gynecologists and obstetricians as well as situation may be the climate of Iran.

5 Conclusion

This study proved CT infection among women in different regions of Iran. Infected women play an important role as sexual activity is responsible for transmission and untreated women are at risk of developing sequels. Different articles and results are performed in this field in Iran. So further studies are needed to be done about CT infection. Most studies in Iran are due to the sensitive nature of PCR tests used for the detection of genital CT infections and less invasive because of urine sampling, because this method is used for sampling.


The authors would like to thank Deputy of Research of Kurdistan University of Medical Sciences for financial support. The authors also appreciate of Social Determinants of Health Research Center and Cellular and Molecular Research Center, Department of Genecology of Kurdistan University of Medical Sciences in Iran.

Author contributions

Data curation: Daem Roshani, Rashid Ramazanzadeh, Fariba Farhadifar, Amjad Ahmadi, Safoura Derakhshan, Samaneh Rouhi, Shamsi Zarea, Farnaz Zandvakili.

Formal analysis: Daem Roshani, Amjad Ahmadi.

Investigation: Fariba Farhadifar, Samaneh Rouhi, Farnaz Zandvakili.

Project administration: Daem Roshani.

Writing – original draft: Amjad Ahmadi.

Writing – review & editing: Rashid Ramazanzadeh, Fariba Farhadifar, Samaneh Rouhi, Shamsi Zarea, Farnaz Zandvakili.


[1]. Cunningham F, Leveno K, Bloom S, et al. Williams Obstetrics. 2014;New York: McGraw-Hill, 24e.
[2]. Nguyen TV, Van Khuu N, Le TTT, et al. Sexually transmitted infections and risk factors for Gonorrhea and Chlamydia in female sex workers in Soc Trang, Vietnam. Sex Transm Dis 2008;35:935–40.
[3]. Stamm WE, Jones RB, Batteiger BE. Mandell GL, Bennett JE, Dolin R. Chlamydia trachomatis (trachoma, perinatal infections, lymphogranuloma venereum, and other genital infections). Elsevier Churchill Livingstone, Principles and Practice of Infectious Diseases. Philadelphia, PA:2005.
[4]. Hanski L, Vuorela P. Lead discovery strategies for identification of chlamydia pneumoniae inhibitors. Microorganisms 2016;4:43.
[5]. Sciarra J. Sexually transmitted diseases: global importance. Int J Gynecol Obstet 1997;58:107–19.
[6]. Duncan B, Hart G. Sexuality and health: the hidden costs of screening for Chlamydia trachomatis. Br Med J 1999;318:931–3.
[7]. Kataoka S, Yamada T, Chou K, et al. Association between preterm birth and vaginal colonization by mycoplasmas in early pregnancy. J Clin Microbiol 2006;44:51–5.
[8]. Silveira M, Ghanem K, Erbelding E, et al. Chlamydia trachomatis infection during pregnancy and the risk of preterm birth: a case-control study. Int J STD AIDS 2009;20:465–9.
[9]. Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 2009;6:e1000097.
[10]. Jenab A, Golbang N, Golbang P, et al. Diagnostic value of PCR and ELISA for Chlamydia trachomatis in a group of asymptomatic and symptomatic women in Isfahan, Iran. Int J Fertil Steril 2009;2:193–8.
    [11]. Jahromi AS, Farjam MR, Mogharrab F, et al. Chlamydia trachomatis in women with full-term deliveries and women with abortion. Am J Infect Dis 2010;3:66–9.
      [12]. Moaiedmohseni S, Owje M. The value of Chlamydia trachomatis antibody testing in prediction of tubal factor infertility. J Family Reprod Health 2008;2:29–32.
        [13]. Afrakhteh M, Beyhaghi H, Moradi A, et al. Sexually transmitted infections in Tehran. J Family Reprod Health 2008;2:123–8.
          [14]. Sattari M, Zeighami H, Peerayea SN. Detection of Chlamydia trachomatis in endocervical smears of women with abortion. Res J Biol Sci 2008;3:214–6.
            [15]. Chamani Tabriz L, Jeddi-Tehrani M, Mosavi-Jarrahi A, et al. The prevalence of Chlamydia trachomatis infection by molecular analysis of urine samples in women attending OB & GYN clinics in Tehran. J Reprod Infertil 2006;7:234–42.
              [16]. Hashemi F, Pourakbari B, Mamishi S, et al. Detection of Chlamydia trachomatis in endocervical specimens by an enzyme-linked polymerase chain reaction assay. DARU J Pharm Sci 2007;15:100–4.
                [17]. Akya A. The frequency of Chlamydia trachomatis and Neisseria gonorrhoeae infections among women in Kermanshah, Iran. Asian Biomed 2013;7:681–5.
                  [18]. Taheri Beni B, Motamedi H, Roayaei Ardakani M. Genotyping of the prevalent Chlamydia trachomatis strains involved in cervical infections in women in Ahvaz, Iran. J Med Microbiol 2010;59:1023–8.
                    [19]. Badami N, Salari M. Rate of Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum in infertile females and control group. Iran J Public Health 2001;30:57–60.
                      [20]. Fallah F, Kazemi B, Goudarzi H, et al. Detection of Chlamydia trachomatis from urine specimens by PCR in women with cervicitis. Iran J Public Health 2005;34:20–6.
                        [21]. Yazdi JZ, Khorramizadeh M, Badami N, et al. Comparative assessment of Chlamydia trachomatis infection in Iranian women with cervicitis: a cross-sectional study. Iran J Public Health 2006;35:69–75.
                          [22]. Salari M, Badami N. The rate of Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum in females with habitual abortion and its comparison with control group. Acta Med Iran 2002;40:79–82.
                            [23]. Farivar TN, Johari P. Lack of association between Chlamydia trachomatis infection and cervical cancer—Taq Man realtime PCR assay findings. Asian Pac J Cancer Prev 2012;13:3701–4.
                              [24]. Hassanzadeh P, Sharifi H, Bazargani A, et al. Non-detection of Chlamydia trachomatis infection by polymerase chain reaction in pregnant Iranian women. Microbiol Res 2012;3:e8.
                                [25]. Dabbaghi Ghaleh T, Lalooha F, Amini F, et al. Assessment Chlamydia trachomatis antibody intubal factor infertility. Novel Sci Int J Med Sci 2012;1:1.
                                  [26]. Behrouzi R, Moussavi Z. The prevalence of Chlamydia infection among pregnant women in Iran: an immunofluorescence study. J Tissue Res 2004;4:249–52.
                                    [27]. Hajikhani B, Motallebi T, Norouzi J, et al. Classical and molecular methods for evaluation of Chlamydia trachomatis infection in women with tubal factor infertility. J Reprod Infertil 2013;14:29–33.
                                      [28]. Hossein Rashidi B, Chamani-Tabriz L, Haghollahi F, et al. Effects of Chlamydia trachomatis infection on fertility: a case-control study. J Reprod Infertil 2013;14:67–72.
                                        [29]. Nazer M, Nowroozi J, Mirsalehian A, et al. Determination of asymptomatic Chlamydia trachomatis infections by Omp1 gene based-PCR. Yakhteh Med J 2008;1:41–6.
                                          [30]. Samarbaf-Zadeh A, Razi MT, Kelishadi M. Prevalence of C. trachomatis infection among Ahvaz females with vaginal discharge. J Fertil Steril 2007;1:19–22.
                                            [31]. Kalantar SM, Kazemi MJ, Sheikhha MH, et al. Detection of Chlamydia trachomatis infection in female partners of infertile couples. Iran J Fertil Steril 2007;1:79–84.
                                              [32]. Peivandi S, Moslemizadeh N, Gharajeh S, et al. The role of Chlamydia trachomatis IgG antibody testing in predicting tubal factor infertility in Northern Iran. Int J Fertil Steril 2009;3:143–8.
                                                [33]. Hadi N, Barazandeh F, Azad F. The prevalence of Chlamydia trachomatis infection in women attending health clinics in Shiraz, Islamic Republic of Iran. Int J Fertil Steril 2010;4:128–33.
                                                  [34]. Hasanabad MH, Mohammadzadeh M, Bahador A, et al. Prevalence of Chlamydia trachomatis and Mycoplasma genitalium in pregnant women of Sabzevar-Iran. Iran J Microbiol 2011;3:123–8.
                                                    [35]. Eslami G, Goudarzi H, Taheripanah R, et al. Chlamydia trachomatis detection by nested-PCR method on females referred to medical centers of Tehran, Iran. Arch Clin Infect Dis 2012;7:124–7.
                                                      [36]. Jenab A, Roghanian R, Golbang N, et al. Comparison of three methods of DNA extraction in endocervical specimens for Chlamydia trachomatis infection by spectrophotometry, agarose gel, and PCR. Arch Immunol Ther Exp 2010;58:227–34.
                                                        [37]. Hamid B, Braham A, Mohtaram H. Prevalence of infection with Nisseria gonorrhoeae and Chlamydia trachomatis in women visitors of gynecology and obstetrics clinics in Zanjan Province of Iran. Afr J Microbiol Res 2011;5:2447–50.
                                                          [38]. Tabasi Z, Badami N, Atabakhshi M, et al. Evaluation of the prevalence of Chlamydia trachomatis and its associated factors in patients with pelvic inflammatory disorders in Shabihkhani Hospital in Kashan in 2000. KAUMS J (FEYZ) 2001;5:43–9.
                                                            [39]. Tayebeh N, Fatemeh K, Abbas B. Comparison of Chlamydia infection prevalence between patients with and without ectopic pregnancy using the PCR method. Ginekol Polska 2012;83:819–21.
                                                              [40]. Afrakhteh M, Mahdavi A, Beyhaghi H, et al. The prevalence of Chlamydia trachomatis in patients who remained symptomatic after completion of sexually transmitted infection treatment. Iran J Reprod Med 2013;11:285.
                                                                [41]. Kajbaf MJ, Gholamnezhad A. Prevalence of Chlamydia trachomatis antigen and antibody in infertile women in Ahwaz. Iran Biomed J 1998;2:45–8.
                                                                  [42]. Fatholahzadeh B, Bahador A, Hasanabad MH, et al. Comparative screening of Chlamydia trachomatis infection in women population in Tehran, Iran. Iran Red Crescent Med J 2012;14:289–93.
                                                                    [43]. Marashi SMA, Moulana Z, Imani Fooladi AA, et al. Comparison of genital Chlamydia trachomatis infection incidence between women with infertility and healthy women in Iran using PCR and immunofluorescence methods. Jundishapur J Microbiol 2014;7:e9450.
                                                                      [44]. Khalili M, Atapour M, Aali S, et al. Frequency of Chlamydia trachomatis in genital specimens: Kerman city, PCR method. Tehran Univ Med J 2008;66:127–30.
                                                                        [45]. Bakhtiari A, Firoozjahi A. Chlamydia trachomatis infection in women attending health centres in Babol: prevalence and risk factors. East Mediterr Health J 2007;13:1124–31.
                                                                          [46]. Khazardoost S, Haghollahi F, Roostaie S, et al. Chlamydia trachomatis infection in pregnant women. J Reprod Infertil 2009;10:121–8.
                                                                            [47]. Sohrabi A, Samarbaf ZA, Mak VM, et al. A seroepidemiological study of parvovirus B19, Toxoplasma gondii and Chlamydia trachomatis in pregnant women referring to Obs & Gyn ward of Ahwaz Imam Khomeini Hospital. Reprod Infertil 2007;8:171–5.
                                                                              [48]. Mohammadzadeh M, Amirmozafari N, Shayanfar N, et al. Prevalence of Chlamydia trachomatis infections in symptomatic women by polymerase chain reaction (PCR) immunofluorescence and Giemsa stain. Afr J Biotechnol 2013;10:6601–5.
                                                                                [49]. Khajehkarramedini M, Hashemi S, Naderinasab M, et al. Frequency of Chlamydia trachomatis infection in cervical and urethral samples referred to Ghaem Hospital of Mashhad. Iran J Obstet Gyneocol Infertil 2011;22:474–7.
                                                                                  [50]. Lewis D, Newton DC, Guy RJ, et al. The prevalence of Chlamydia trachomatis infection in Australia: a systematic review and meta-analysis. BMC Infect Dis 2012;12:113.
                                                                                  [51]. Adams E, Charlett A, Edmunds W, et al. Chlamydia trachomatis in the United Kingdom: a systematic review and analysis of prevalence studies. Sex Transm Infect 2004;80:354–62.
                                                                                  [52]. Watson EJ, Templeton A, Russell I, et al. The accuracy and efficacy of screening tests for Chlamydia trachomatis: a systematic review. J Med Microbiol 2002;51:1021–31.
                                                                                  [53]. Cook RL, Hutchison SL, Østergaard L, et al. Systematic review: noninvasive testing for Chlamydia trachomatis and Neisseria gonorrhoeae. Ann Intern Med 2005;142:914–25.

                                                                                  Chlamydia trachomatis; infection; Iranian women; meta-analysis

                                                                                  Copyright © 2018 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.