Hirohisa Imai

National Institute of Health Sciences, Japan, Edo, Tōkyō, Japan

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Publications (59)125.66 Total impact

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    ABSTRACT: Background and methods: We conducted a community-based study to evaluate genotype-specific prevalence of high-risk HPV (HR-HPV) and potential predictors of its presence in young, asymptomatic, female college students. Self-administered surveys and vaginal swabs for self collection were distributed to students of participating schools. A sufficient cellular component in cervical samples was verified by examining for the presence of human β-globin DNA by PCR. A total of 1,118 valid cervical samples were subjected to screening for HR-HPV infection with the Digene Hybrid Capture 2 assay, followed by identification of HPV genotypes with GENOSEARCH HPV31 kit. Logistic regression was used to adjust for confounding factors associated with HR-HPV positivity and the adjusted odds ratio (AOR) was calculated. Results: The median age of recruited students was 20 years. Of the 1,118 women who provided valid cervical samples for testing, 770 had sexual intercourse in the past, of which 125 (16.2%) were positive for HR-HPV. Logistic regression analysis revealed that HR-HPV infection was associated with smoking history (AOR 2.13; 95% confidence interval [CI] 1.98 to 5.05; p < 0.01), total number of partners (AOR 4.72; 95% CI 1.97 to 11.32 if > 5 partners; p < 0.001), number of partners in the past 6 months (AOR 3.12; 95% CI 1.42 to 6.87; p < 0.01), improper use of condoms (AOR 2.21; 95% CI 1.25 to 3.90; p < 0.01), and chlamydia infection (AOR 2.61; 95% CI 1.28 to 5.34; p < 0.01). The most common HR-HPV genotype was type 52 (6.4%), followed by 16 (3.1%), 56 (3.0%), and 58 (2.6%). Conclusion: Compared with previous reports in East Asian coutries, the prevalence of HR-HPV infection among young, asymptomatic, female students before the nationwide use of vaccination in Japan was in the intermediate range. The most common HR-HPV genotypes were HPV 52, 16, 56, and 58.
    PLoS ONE 07/2015; 10(7):e0132462. DOI:10.1371/journal.pone.0132462 · 3.23 Impact Factor
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    ABSTRACT: We investigated incidence and risk factors for postextraction bleeding in patients receiving warfarin and those not receiving anticoagulation therapy. Cross-sectional, multicentre, observational study. 26 hospitals where an oral surgeon is available. Data on 2817 teeth (from 496 patients receiving warfarin, 2321 patients not receiving warfarin; mean age (SD): 62.2 (17.6)) extracted between 1 November 2008 and 31 March 2010, were collected. Warfarin-receiving patients were eligible when prothrombin time-international normalised ratio (PT-INR) measured within 7 days prior to the extraction was less than 3.0. Simple dental extraction was performed, and incidence of postextraction bleeding and comorbidities were recorded. Postextraction bleeding not controlled by basic haemostasis procedure was clinically significant. Bleeding events were reported for 35 (7.1%) and 49 (2.1%) teeth, of which 18 (3.6%) and 9 (0.4%) teeth were considered clinically significant, in warfarin and non-warfarin groups, respectively, the difference between which was 3.24% (CI 1.58% to 4.90%). The incidence rates by patients were 2.77% and 0.39%, in warfarin and non-warfarin groups, respectively (incidence difference 2.38%, CI 0.65% to 4/10%). Univariate analyses showed that age (OR 0.197, p=0.001), PT-INR (OR 3.635, p=0.003), mandibular foramen conduction anaesthesia (OR 4.854, p=0.050) and formation of abnormal granulation tissue in extraction socket (OR 2.900, p=0.031) significantly correlate with bleeding incidence. Multivariate analysis revealed that age (OR 0.126, p=0.001), antiplatelet drugs (OR 0.100, p=0.049), PT-INR (OR 7.797, p=0.001) and history of acute inflammation at extraction site (OR 3.722, p=0.037) were significant risk factors for postextraction bleeding. Our results suggest that there is slight but significant increase in the incidences of postextraction bleeding in patients receiving warfarin. Although absolute incidence was low in both groups, the bleeding risk is not negligible. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    BMJ Open 12/2014; 4(12):e005777. DOI:10.1136/bmjopen-2014-005777 · 2.27 Impact Factor
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    ABSTRACT: OBJECTIVES: To determine whether foreskin status is a measurable marker for evaluating the effect of the foreskin on sexually transmitted infections. METHODS: Inter-rater comparison of the responses on foreskin status and circumcision in a self-report questionnaire with the findings of a physical examination by an experienced well-trained urologist was performed for patients who visited a healthcare facility in Kanagawa, Japan. Foreskin status was defined using a five-point graphical scale based on the degree to which the foreskin covers the foreskin and the glans penis in a non-erectile condition: type 1, a fully exposed glans penis; types 2-4, the glans penis partly covered by the foreskin and type 5, phimosis. Linear weighted κ and per cent agreement were used to evaluate the reliability of responses. RESULTS: Among 188 participants who were evaluated about their foreskin status, linear weighted κ and per cent agreement were 0.74% and 68.4%, respectively. Linear weighted κ improved from 0.74 to 0.80 when the number of categories was changed to three. All the self-reported responses on circumcision were in agreement with the findings of the physical examination. Seventeen participants (9.0%) had been circumcised, and among them, three (17.6%) had approximately one-half of their glans penis covered by the foreskin. In 90 among the 171 uncircumcised participants (52.6%), the foreskin did not cover the glans penis. CONCLUSIONS: The self-reported response on foreskin status in this questionnaire has sufficient reliability to replace physical examination, and this questionnaire can facilitate further studies about the effect of foreskin on sexually transmitted infections.
    Sexually transmitted infections 05/2012; 88(7). DOI:10.1136/sextrans-2011-050294 · 3.40 Impact Factor
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    ABSTRACT: Hyposalivation may affect respiratory disease because the mouth serves as the entrance to the respiratory apparatus, as well as to the digestive tract. Patients with acute respiratory infection generally have a favorable prognosis and a short natural course. However, in cases in which the host has lowered resistance, such as in elderly patients, the infection may develop into pneumonia. A prospective study was performed to examine the relationship between hyposalivation, which is common in elderly patients, and acute respiratory infection, which tends to become severe in elderly patients. The subjects were 323 male and female patients ≥40 years old who lived in Utsunomiya City and surrounding areas and regularly visited the Department of Dentistry and Oral Surgery, Tochigi National Hospital. A 6-month follow-up survey was performed to examine development of acute respiratory infection. Age, sex, and known risk factors were also investigated. Hyposalivation was defined as a saliva production (saliva secretion rate) of ≤0.6 ml/min. Multivariate analysis adjusted for age and sex was performed to examine potential risk factors associated with the development of acute respiratory infection. Data were analyzed for 278 subjects who completed the follow-up survey. The incidence of acute respiratory infection was 60.4%, while hyposalivation was present in 96 subjects (35.5%). Multivariate analysis showed that the incidence of acute respiratory infection was higher in subjects with hyposalivation than in those without hyposalivation (adjusted odds ratio 1.761, p = 0.048). The results of this study suggest that hyposalivation may be a risk factor for acute respiratory infection. This also suggests that improvement of hyposalivation might prevent acute respiratory infection.
    Gerontology 11/2011; 58(3):205-11. DOI:10.1159/000333147 · 3.06 Impact Factor
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    H. Imai · H. Nakao · F. Sata
    Value in Health 11/2011; 14(7). DOI:10.1016/j.jval.2011.08.595 · 3.28 Impact Factor
  • F. Sata · H. Imai · H. Nakao · Y. Fukuda
    Journal of Epidemiology &amp Community Health 08/2011; 65:A156-A156. DOI:10.1136/jech.2011.142976f.12 · 3.50 Impact Factor
  • Epidemiology 01/2011; 22:S123. DOI:10.1097/01.ede.0000392047.53558.a0 · 6.20 Impact Factor
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    ABSTRACT: Hypospadias is a common congenital anomaly caused by incomplete fusion of urethral folds. Development of the urethra and external genital system in the male fetus is an androgen-dependent process. In this regard, enzymes 17 β-hydroxysteroid dehydrogenase type 3 (17 β HSD3, encoded by HSD17B3) and steroid 5 α-reductase type 2 (encoded by SRD5A2) play crucial roles. To investigate the possible associations between common polymorphisms in HSD17B3 as well as well-known V89L polymorphism in SRD5A2 and risk of hypospadias. A case-control study was performed between 1999 and 2005. There were 89 Japanese boys with hypospadias and 291 newborn controls. We genotyped HSD17B3-1999T>C, +10A>G, +20A>G, +139G>A (V31I), +913G>A (G289S), and SRD5A2+336G>C (V89L) polymorphisms by allelic discrimination assay. We measured mRNA expression of the wildtype G289 allele and the mutant S289 allele of the HSD17B3 gene in the transfected human fetal kidney HEK293 cells. Assessment of hypospadias including its severity and HSD17B3 and SRD5A2 genes using DNA blood samples: allele and genotype distribution of single nucleotide polymorphisms in these two genes in cases and controls. In our study, the risk of hypospadias was significantly higher in subjects carrying homozygous HSD17B3+913A (289S) alleles (odds ratio [OR]: 3.06; 95% confidence interval [CI]: 1.38-6.76). The risk of severe hypospadias was much higher in these subjects (OR: 3.93; 95% CI: 1.34-11.49). The mRNA expression levels of HSD17B3 G289 were higher than those of HSD17B3 S289 mutant (P < 0.001). In addition, the risk of severe hypospadias increased in boys carrying the SRD5A2+336C (89L) allele (OR: 3.19; 95% CI: 1.09-9.36). These results suggest that the HSD17B3 G289S polymorphism may be a potential risk modifier for hypospadias. Our findings provide evidence that a certain genotype related to androgen production may potentiate risk of hypospadias.
    Journal of Sexual Medicine 08/2010; 7(8):2729-38. DOI:10.1111/j.1743-6109.2009.01641.x · 3.15 Impact Factor
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    ABSTRACT: We explored the relationship between bone mineral density (BMD) and lifestyle in juveniles to identify factors leading to higher peak bone mass and prevention of osteoporosis in later life. Juveniles (1,364 students: 770 boys and 594 girls, aged 6-18 years) attending school in Hokkaido prefecture, Japan, were asked to complete a brief self-administered diet history questionnaire for 10-year-olds (BDHQ10y) providing information about personal history, lifestyle, and intake of nutritional elements. In addition, BMD and grip strength were measured. We analyzed the relationship between BMD and lifestyle factors. The difference in BMD for boys was larger among the junior and senior high school groups. The difference in BMD for girls was larger among older elementary and later school children. Anthropometric variables and grip strength were strongly correlated with BMD. Having a nap-time routine was significantly correlated with BMD, but sleep time and sports club activities were not. BMD among juveniles who attained secondary sexual characteristics was significantly higher than that of juveniles of the same age who had not attained these characteristics. Calcium intake was significantly lower in senior high school students compared with other grades. Consumption of milk by senior high school boys and junior high school girls was weakly correlated with BMD. Our findings encourage educational interventions to counsel students to avoid weight loss and calcium deficiency. This effective intervention should begin before the higher elementary school, when juveniles have the greatest likelihood for preventing lower peak bone mass and osteoporosis.
    Environmental Health and Preventive Medicine 07/2010; 15(4):222-8. DOI:10.1007/s12199-009-0131-8
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    ABSTRACT: There are few epidemiological studies of asymptomatic chlamydial infection among students in non-medical settings with minimal bias and improved accuracy; thus, useful data from screening among students are limited. We aimed to obtain accurate epidemiological information about asymptomatic chlamydial infection among students in non-medical settings. A population-based cross-sectional survey of 10,440 >or=18-year-old asymptomatic students who volunteered for a urine screening test for chlamydia was conducted. The prevalences of asymptomatic infection were 9.5% for women and 6.7% for men. Multivariate analysis revealed the risk factors to be a lifetime history of >or=4 sexual partners for women (odds ratio [OR] 3.17) and inconsistent condom use for men (OR 4.18). For both sexes, younger age at first intercourse was associated with a higher rate of inconsistent condom use. This study produced accurate epidemiological information on asymptomatic chlamydial infection. These results may contribute to the establishment of preventive countermeasures against such infection.
    International Journal of STD & AIDS 05/2010; 21(5):362-6. DOI:10.1258/ijsa.2010.010026 · 1.05 Impact Factor
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    ABSTRACT: Background: Smoking is a leading risk factor for a wide variety of diseases ranging periodontitis to cancer. Adults rarely visit their physicians for preventive care. But a survey shows that more than half of adult smokers see a dentist each year for prevention-oriented care. This may put dentists in better position to intervene for smoking cessation. Objective: This study examined Japanese dentists' attitudes and practices regarding smoking cessation. Methods: The study used a survey mailed to dentists (n=1489) in three prefectures (Tokyo, Iwate, Yamanashi) asking about the practitioners' smoking cessation activities, demographic characteristic, barriers to counseling and attitudes towards smoking. Results: The response rate was 57% (n=847). Dentists advised 22% of patients to cease smoking. More than half of them used a pamphlet or similar. However, nicotine replacement therapy was prescribed infrequently (7%). Asked whether a dentist should apply smoking cessation activities in their office 76% replied Yes. The main barrier to cessation counseling was insufficient time, followed by a lack of knowledge and smoking cessation experts to refer to. 85% of respondents had no education or training in promoting smoking cessation. 22% of all responding dentists were smokers. Conclusion: Few dentists conduct smoking cessation activities in their office. Dental professionals should develop a willingness to play a more positive role in relevant smoking cessation activities despite numerous barriers.
    137st APHA Annual Meeting and Exposition 2009; 11/2009
  • Epidemiology 11/2009; 20. DOI:10.1097/01.ede.0000362595.13847.6b · 6.20 Impact Factor
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    H Imai · H Nakao · F Sata · Y Fukuda
    Value in Health 10/2009; 12(7). DOI:10.1016/S1098-3015(10)74402-8 · 3.28 Impact Factor
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    H Nakao · I Yoshimi · Y Fukuda · F Sata · H Imai
    Value in Health 10/2009; 12(7). DOI:10.1016/S1098-3015(10)74510-1 · 3.28 Impact Factor
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    ABSTRACT: [Background] The national health project for lifestyle-related disease control with particular emphasis on metabolic syndrome (central obesity, impaired glucose tolerance, hypertension, dyslipidaemia) was inaugurated in April 2008. However, this project was introduced before its methodologies were adequately established; therefore, an evidence-based health policy is now desired. [Purpose] We carried out a pilot study in 2007 prior to the implementation of public health measures, developed a health guidance program in which community-based nutritional and exercise guidance is incorporated, carried out the program as a trial, and evaluated the program in terms of its validity and feasibility. [Methods] The participants of this program consisted of 311 local residents (135 males and 176 females; mean age, 61.4) with impaired glucose tolerance. A nutritional guidance program, including guidance on such items as suppression of total calories consumed per day, energy from fat of 25% or less, 10 g of salt or less, and 25 g of fiber per day or more, was developed considering the physique of the Japanese and was implemented by the participants. Regarding exercise guidance, they were instructed to walk more than 10,000 steps/day as determined using a pedometer. This comprehensive program was carried out for six months. [Results] After the program’s completion, the participants’ mean weight decreased from 63.8 to 62.1 kg (p<0.001), abdominal circumference from 91.6 to 89.5 cm (p<0.001), and HbA1c level from 5.42 to 5.25% (p<0.001). The percentage of participants whose satisfaction level was either “very satisfactory” or “satisfactory” reached 96.8%. [Discussion] Our comprehensive health guidance program incorporating community-based nutritional and exercise guidance had a significant impact and its feasibility was demonstrated. We obtained our results of the program’s evaluation six months after its implementation; long-term analyses of the effect of the program will be necessary in the future.
    12th World Congress on Public Health World Health Organization; 04/2009
  • Hirohisa Imai · Yuichiro Yahata · Hiroyuki Nakao
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    ABSTRACT: Objective: To try a new screening strategy for asymptomatic chlamydial infection among students for more accurate and efficient screening of infected individuals in nonmedical settings. Methods: Population-based cross-sectional surveys were carried out in campus settings for general student populations using anonymous identification numbers and polymerase chain reaction testing of urine specimens for Chlamydia trachomatis; online access to test results via mobile phones was provided. All universities and junior colleges and most professional schools in a prefecture in Japan took part in this screening program. Subjects comprised 10,111 asymptomatic student volunteers 18 and over years old (5986 females, 4125 males). Prevalence and risk factors of asymptomatic infection were determined on the basis of survey results for subjects with positive results to urine testing for C. trachomatis. Results: The prevalence of asymptomatic chlamydial infection was 9.6% for females and 6.7% for males. Lifetime history of 4 and over sexual partners (females: odds ratio, 3.46; 95% confidence interval, 2.63-4.58; males: 1.90; 1.28-2.81), inconsistent condom use (females: 2.52; 1.78-3.57; males: 4.00; 2.44-6.59), and 6-month history of 2 and over sexual partners (females: 1.55; 1.19-2.03; males: 1.48; 1.01-2.17) represented significant risk factors for both sexes. Using lifetime history of 4 and over sexual partners or inconsistent condom use as selective criteria allowed detection of 90.4% of infected females from 43.2% of the screened female population, and detection of 87.4% of infected males from 40.0% of the screened male population. Conclusions: On the basis of the resulting accurate epidemiological data, using risky sexual behaviors as a simple selective criteria will allow for efficient screening of infected individuals in nonmedical settings.
    136st APHA Annual Meeting and Exposition 2008; 10/2008
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    ABSTRACT: Routine immunization is one of the most cost-effective interventions for the prevention of infectious disease. We have investigated the factors associated with the completion of five routine immunizations in Japan. About one thousand children who underwent a health checkup from April to December in 2004 participated in the study. A structured questionnaire was used to collect information on characteristics of the child: age at immunization, guardians' knowledge and attitude, and Child-Rearing. Immunization coverage rate was calculated. Associations between immunization and knowledge and attitude were calculated to get crude and adjusted odds ratios, using a logistic regression analysis. The coverage rate for the five vaccines was 70.5% in children under 3-year-old. BCG had the highest coverage rate (94.2%) of the five vaccines. The best source of information was notification from the local government at 92.4%. Completion of the administration of five immunizations was significantly associated with PCH-Pocketbook (OR=1.31, 95%CI:1.01-1.70); Child-Rearing Magazine (OR=1.77, 95%CI:1.23-2.55); intention to finish all the immunizations (OR=2.93, 95%CI:2.20-3.91); child care at a nursing school during the day (OR=0.49, 95%CI:0.37-0.64); and living in an urban area (OR=1.33, 95%CI:1.02-1.73). Adjusted odds ratios included child care at a nursing school during the day and living in an urban area, and they were significantly associated with Child-Rearing Magazine (OR=1.82, 95%CI:1.25-2.64) and intention to finish all the immunizations (OR=3.00, 95%CI:2.23-4.03). Our results suggested that Child-Rearing Magazine and scheduling all the immunizations promoted the administration of five vaccines to children under 3-year-old until newspapers and television suppressed the administration of the vaccines.
    136st APHA Annual Meeting and Exposition 2008; 10/2008
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    ABSTRACT: Long-term care (LTC) insurance was introduced in Japan in 2000. Herein, we describe the trends in demand for LTC, using age-standardized and level-specific rates of entitlement and utilization of LTC at national and prefectural levels. We analyzed LTC data from 2002-2005 to examine: (i) the influence of population aging, calculating crude and age-standardized entitlement and utilization rates; (ii) the relation between baseline entitlement rate and increase in the rate over this 3-year period; and (iii) differences in increases in entitlement rate between low and high care levels. The entitlement and utilization rates increased even after adjustment for age; approximately two-thirds of the increase was not due to population aging. Variations in the entitlement rates among prefectures did not decrease (coefficient of variance was 0.12 in 2002 and 0.11 in 2005), and there was no significant correlation between baseline entitlement rates and the later increases among prefectures (r = -0.20, P = 0.19). The increase in entitlement rate was larger for low than for high care levels (31% vs 6%), and those for low and high care levels were weakly correlated. This study suggested that a large part of the increase in LTC demand could not be explained by population aging, and the increase did not result from equalization of LTC services across the country. In addition, it seems that the demands of low and high care levels depend on different factors. The increase in LTC demand should be monitored carefully to identify underlying factors and to ensure sustainability of the system.
    Geriatrics & Gerontology International 10/2008; 8(3):166-71. DOI:10.1111/j.1447-0594.2008.00466.x · 2.19 Impact Factor
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    ABSTRACT: A long-term care insurance (LTCI) system was introduced in 2000 in Japan. The clarification of information on the users and the ways in which services under this system have been utilized is essential for improving the system operation. This study was conducted for the purpose of clarifying what level of health-related quality of life (HRQOL) was achieved by individuals using the services under the LTCI system. The subjects were inhabitants of two cities in the Kyushu district of Japan who were receiving daily home care services under the LTCI system. To analyze the relationships of the beneficiaries' HRQOL with their characteristics, the dependent variable was the EuroQol-5D (EQ-5D) scores adopted as an index of HRQOL, and the independent variables comprised the demographic features (gender, age, and living condition) of users receiving long-term care service as well as their opinions about fees for services, satisfaction with the services provided, and the degree of support/care required. The EQ-5D score was higher for females than for males and higher for the subjects living alone than for those displaying any other family composition. EQ-5D score decreased with an increase in the degree of support/care required. Multivariate analysis revealed that the degree of support/care required, gender and living condition were found to serve as variables that significantly contribute to utility. Our analysis of the relationships between the characteristics of the LTCI beneficiaries and their HRQOL has yielded basic data that will be useful for improving the recently introduced LTCI system.
    Health Policy 04/2008; 85(3):349-55. DOI:10.1016/j.healthpol.2007.08.008 · 1.91 Impact Factor
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    R Hamasuna · H Imai · H Tsukino · J S Jensen · Y Osada
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    ABSTRACT: In Japan it was reported that about 9% of sexually active female teenagers had Chlamydia trachomatis. Most of them were asymptomatic, which may lead to continuing spread of the infection. Like C trachomatis, Mycoplasma genitalium is a pathogen in male non-gonococcal urethritis. However, few studies of the prevalence of M genitalium in the general population have been reported. The objective of this study was to determine the prevalence of M genitalium infection among younger females and to determine risk factors for this infection. The study was conducted between October 2005 and January 2006 using first voided urine specimens and questionnaires from female students of three vocational schools in the Miyazaki prefecture, Japan. C trachomatis was detected with Amplicor PCR. M genitalium was detected with inhibitor controlled real-time TaqMan PCR detecting the MgPa adhesion gene and with a PCR detecting the 16S rRNA. Risk factors associated with infection of M genitalium or C trachomatis were analysed with Fisher's exact test. Among 298 female, 249 (84%) had had experience of sexual intercourse. The prevalence of M genitalium was 2.8% (95% CI 0.76% to 4.86%) and the prevalence of C trachomatis was 8.8% (95% CI 5.31% to 12.36%). The risk factors of infection with M genitalium were more than five lifetime sexual partners and co-infection with C trachomatis.
    Sexually transmitted infections 02/2008; 84(4):303-5. DOI:10.1136/sti.2007.028670 · 3.40 Impact Factor

Publication Stats

591 Citations
125.66 Total Impact Points


  • 2014
    • National Institute of Health Sciences, Japan
      Edo, Tōkyō, Japan
  • 2006–2011
    • National Institute of Public Health
      Saitama, Saitama, Japan
  • 2007
    • Shikoku Cancer Center
      Matuyama, Ehime, Japan
  • 2004–2005
    • Miyazaki University
      • Faculty of Medicine
      Миядзаки, Miyazaki, Japan
  • 2002
    • Tokyo Metropolitan Police Hospital
      Edo, Tōkyō, Japan