The Netherlands Chlamydia cohort study (NECCST) protocol to assess the risk of late complications following Chlamydia trachomatis infection in women

Background

Chlamydia trachomatis (CT), the most common bacterial sexually transmitted infection (STI) among young women, can result in serious sequelae. Although the course of infection is often asymptomatic, CT may cause pelvic inflammatory disease (PID), leading to severe complications, such as prolonged time to pregnancy, ectopic pregnancy, and tubal factor subfertility. The risk of and risk factors for complications following CT-infection have not been assessed in a long-term prospective cohort study, the preferred design to define infections and complications adequately.

Methods

In the Netherlands Chlamydia Cohort Study (NECCST), a cohort of women of reproductive age with and without a history of CT-infection is followed over a minimum of ten years to investigate (CT-related) reproductive tract complications. This study is a follow-up of the Chlamydia Screening Implementation (CSI) study, executed between 2008 and 2011 in the Netherlands. For NECCST, female CSI participants who consented to be approached for follow-up studies (n = 14,685) are invited, and prospectively followed until 2022. Four data collection moments are foreseen every two consecutive years. Questionnaire data and blood samples for CT-Immunoglobulin G (IgG) measurement are obtained as well as host DNA to determine specific genetic biomarkers related to susceptibility and severity of infection. CT-history will be based on CSI test outcomes, self-reported infections and CT-IgG presence. Information on (time to) pregnancies and the potential long-term complications (i.e. PID, ectopic pregnancy and (tubal factor) subfertility), will be acquired by questionnaires. Reported subfertility will be verified in medical registers. Occurrence of these late complications and prolonged time to pregnancy, as a proxy for reduced fertility due to a previous CT-infection, or other risk factors, will be investigated using longitudinal statistical procedures.

Discussion

In the proposed study, the occurrence of late complications following CT-infection and its risk factors will be assessed. Ultimately, provided reliable risk factors and/or markers can be identified for such late complications. This will contribute to the development of a prognostic tool to estimate the risk of CT-related complications at an early time point, enabling targeted prevention and care towards women at risk for late complications.

Trial registration

Dutch Trial Register NTR-5597. Retrospectively registered 14 February 2016.

Ethnic and regional differences in STI clinic use: a Dutch epidemiological study using aggregated STI clinic data combined with population numbers

OBJECTIVES

Ethnic minorities (EM) from STI-endemic countries are at increased risk to acquire an STI. The objectives of this study were to investigate the difference in STI clinic consultation and positivity rates between ethnic groups, and compare findings between Dutch cities.

METHODS

Aggregated population numbers from 2011 to 2013 of 15-44 year-old citizens of Amsterdam, Rotterdam, The Hague and Utrecht extracted from the population register (N=3 129 941 person-years) were combined with aggregated STI clinic consultation data in these cities from the national STI surveillance database (N=113 536). Using negative binomial regression analyses (adjusted for age and gender), we compared STI consultation and positivity rates between ethnic groups and cities.

RESULTS

Compared with ethnic Dutch (consultation rate: 40.3/1000 person-years), EM from Eastern Europe, Sub-Sahara Africa, Suriname, the Netherlands Antilles/Aruba and Latin America had higher consultation rates (range relative risk (RR): 1.27-2.26), whereas EM from Turkey, North Africa, Asia and Western countries had lower consultation rates (range RR: 0.29-0.82). Of the consultations among ethnic Dutch, 12.2% was STI positive. Positivity rates were higher among all EM groups (range RR: 1.14-1.81). Consultation rates were highest in Amsterdam and lowest in Utrecht independent of ethnic background (range RR Amsterdam vs Utrecht: 4.30-10.30). Positivity rates differed less between cities.

CONCLUSIONS

There were substantial differences in STI clinic use between ethnic groups and cities in the Netherlands. Although higher positivity rates among EM suggest that these high-risk individuals reach STI clinics, it remains unknown whether their reach is optimal. Special attention should be given to EM with comparatively low consultation rates.

Prognosis after a first hospitalisation for acute myocardial infarction and congestive heart failure by country of birth

OBJECTIVE

To investigate differences in 28-day and 5-year mortality and 5-year readmission after a first hospitalisation for acute myocardial infarction (AMI) and congestive heart failure (CHF) between first generation ethnic minority groups (henceforth, migrants) and the ethnic Dutch population.

METHODS

Nationwide prospective cohorts of first hospitalised AMI (N=213 630) and CHF patients (N=189 069) between 1998 and 2010 were built. Differences in 28-day and 5-year mortality and in 5-year AMI/CHF readmission between migrants (Surinamese, Moroccan, Turkish, Antillean, Indonesian, Chinese and South Asian) and the ethnic Dutch population were investigated using Cox proportional hazard regression models.

RESULTS

After the first AMI hospitalisation, mortality and AMI/CHF readmission were higher in the majority of migrant groups compared with ethnic Dutch. For example, HRs (adjusted for age, sex, marital status, degree of urbanisation and year of event) with 95% CIs among Surinamese (mainly of African or South-Asian origin) were 1.16 (1.02 to 1.32) for 28-day mortality, 1.44 (1.30 to 1.60) for 5-year mortality, 1.33 (1.08 to 1.63) for AMI readmission and 2.09 (1.82 to 2.40) for CHF readmission. After a first CHF hospitalisation, mortality rates among migrants were more diverse, with lower 28-day mortality among Moroccan and Turkish migrants and higher 5-year mortality among Surinamese, Chinese and South Asians. Readmission after CHF was often higher among migrant groups.

CONCLUSIONS

Prognosis after a first AMI hospitalisation was worse among most migrant groups compared with the ethnic Dutch population. Ethnic inequalities in prognosis after a first CHF hospitalisation were more diverse. Efforts should be made to disentangle the underlying factors of the results.

Incidence of first acute myocardial infarction over time specific for age, sex, and country of birth

OBJECTIVES

To study the age- and sex-specific incidence rates of first acute myocardial infarction (AMI) among first-generation ethnic minority groups (henceforth, migrant groups) and the Dutch majority population in the Netherlands during two time periods (2000-2004 and 2005-2010).

METHODS

Through linkage of Dutch nationwide registers, first AMI events in the Dutch majority population and the major migrant groups living in the Netherlands were identified from 2000-2004 and 2005-2010. Absolute incidence rates were calculated within each age-sex-period-country of birth group.

RESULTS

Regardless of ethnic background, AMI incidence rates were higher in men than in women and increased with age. Incidence significantly declined over time among the Dutch majority population (men: -26.8%, women: -26.7%), and among most migrant groups under study. It was only in Moroccan migrants that AMI incidence significantly increased over time (men: 25.2%, women: 41.7%). Trends differed between age categories, but did not show a consistent pattern. The higher AMI incidence in Surinamese men and women and Turkish and Indonesian men compared with the Dutch majority population persisted over time, but decreased with age and became absent after 70 years of age. Moroccans had a significantly lower incidence compared with the Dutch majority population during 2000-2004, which disappeared during 2005-2010.

CONCLUSION

Primary preventive strategies should focus on Surinamese men and women and Turkish and Indonesian men below 70 years of age. Future research is necessary to unravel the factors that provoke the increasing AMI incidence over time among Moroccans.

Socioeconomic inequalities in acute myocardial infarction incidence in migrant groups: has the epidemic arrived? analysis of nation-wide data

OBJECTIVES

We assessed socioeconomic inequalities in relation to acute myocardial infarction (AMI) incidence among major ethnic groups in The Netherlands.

METHODS

A nationwide register-based cohort study was conducted (n=2 591 170) between 1 January 1998 and 31 December 2007 among ethnic Dutch and migrant groups from Suriname, Netherlands Antilles, Indonesia, Morocco and Turkey. Standardised household disposable income was used as a proxy for socioeconomic position. Cox proportional hazard models were used to estimate the socioeconomic inequalities in AMI incidence.

RESULTS

Among ethnic Dutch, the AMI incidence was higher in the low-income group than in the high-income group: adjusted HRs were 2.05 (95% CI 2.00 to 2.10) for men and 2.33 (95% CI 2.23 to 2.43) for women. Importantly, similar socioeconomic inequalities in AMI incidence were also observed in all minority groups, with the low socioeconomic group having a higher AMI incidence than the high socioeconomic group: adjusted HR ranging from 2.07 (95% CI 1.26 to 3.40) in Moroccans to 2.73 (95% CI 1.55 to 4.80) in Antilleans in men; and from 2.17 (95% CI 1.74 to 2.71) in Indonesians to 3.88 (95% CI 2.36 to 6.38) in Turks in women.

CONCLUSIONS

Our findings demonstrate socioeconomic inequalities in AMI incidence in migrant groups and suggest a convergence towards the Dutch general population. If the AMI incidence rates of the low socioeconomic group could be reduced to the level of the high socioeconomic group, this would represent a major public health improvement for all ethnic groups.

Incidence of acute myocardial infarction in first and second generation minority groups: does the second generation converge towards the majority population?

BACKGROUND

Differences in acute myocardial infarction (AMI) incidence between ethnic minority and migrant groups (henceforth, minority groups) and the majority population have been reported. Health differences may converge towards the majority population over generations. We assessed whether AMI incidence differences between minority groups living in the Netherlands and the Dutch majority population exist, and whether the incidence converges towards the majority population over generations.

METHODS

A nationwide register-based cohort study was conducted from 1997 to 2007. Using Cox Proportional Hazard Models AMI incidence differences between minorities and the majority population were estimated. When possible, analyses were stratified by generation.

RESULTS

AMI incidence differences between minorities and the majority population depended on the country of origin, and often varied between minorities originating from the same geographical region. For example, among North African and Mediterranean minorities, incidence was higher in Turkish (Hazard Ratio (HR): 1.34; 95% Confidence Interval (95% CI): 1.28-1.41), but lower in Moroccans (HR: 0.46; 95% CI: 0.40-0.52) compared with the majority population. Most minorities had a similar or lower incidence than the majority population, which remained similar or converged towards the incidence of the majority population over generations. In contrast, among minorities from the former Dutch colonies (Suriname, Indonesia, Netherlands Antilles) beneficial intergenerational changes were observed.

CONCLUSIONS

Health care professionals and policy makers should be aware of substantial AMI incidence differences between minority groups and the majority population, and the often unbeneficial change over generations. Future research should be cautious when clustering minority groups based on geographical region of the country of origin.

Serum micronutrient concentrations and childhood asthma: the PIAMA birth cohort study

BACKGROUND

Research suggests an influence of micronutrients on childhood asthma. So far, evidence mainly originates from cross-sectional studies using nutrient intake data, which is not an accurate measure of nutrient status. This study aimed to investigate the cross-sectional and prospective associations between serum concentrations of magnesium, vitamin D, selenium, and zinc and prevalence of (severe) asthma, atopy, and bronchial hyperresponsiveness (BHR) in childhood.

METHODS

In the Prevention and Incidence of Asthma and Mite Allergy birth cohort study, serum nutrient concentrations were available for a 4-yr-old subgroup (n = 372) and for a different 8-yr-old subgroup (n = 328). Yearly questionnaires inquired about asthma prevalence until 8 yr of age. Allergic sensitization was measured at 4 and 8 yr of age; BHR was measured at 8 yr of age. Data were analyzed with logistic regression and generalized estimating equations models.

RESULTS

There was a consistent (non-significant) inverse association between serum magnesium concentrations and asthma prevalence. Serum vitamin D concentrations measured at age 4 were inversely associated with asthma at ages 4-8 [e.g., cross-sectional association between vitamin D tertile 3 vs. 1 and severe asthma: odds ratio (OR): 0.49, 95% confidence interval (CI): 0.25-0.95], whereas vitamin D measured at age 8 was positively associated with asthma at age 8 (e.g., cross-sectional association between vitamin D tertile 3 vs. 1 and severe asthma: OR: 2.14, 95% CI: 0.67-6.82).

CONCLUSIONS

Our study contributes to the evidence that children with higher serum magnesium concentrations are less likely to have asthma. The associations between serum vitamin D concentrations and asthma were age-dependent.