An epidemiological study of rotavirus diarrhoea in a cohort of Nigerian infants: I. Methodology and experiences in the recruitment and follow-up of patients

Chlamydial infection during trachoma monitoring: are the most difficult-to-reach children more likely to be infected?

OBJECTIVES

During mass antibiotic distributions for trachoma, certain individuals are difficult to locate and go untreated. These untreated individuals may serve as a source of community reinfection. The importance of this difficult-to-locate, untreated population is unclear. We sought to determine whether individuals who are difficult to locate were more likely to be infected with ocular chlamydia than those who were easier to locate.

METHODS

We monitored 12 Ethiopian communities 1 year after a third annual mass azithromycin treatment for trachoma. Conjunctival swabbing for chlamydial RNA was performed in a random sample of children from each community. If insufficient numbers of children were enrolled on the first monitoring day, we returned on subsequent days.

RESULTS

Of the 12 communities, 10 required more than one monitoring day. On average, 16.1% (95% CI 7.9-30.0) of children were enrolled after the initial day. Evidence of chlamydia was found in 7.1% (95% CI 2.7-17.4) of 0- to 9-year-old children. No ocular swabs collected after the initial day were positive for chlamydial RNA. Children examined after the initial monitoring day were significantly less likely to have ocular chlamydial infection than children seen on the initial day; Mantel-Haenszel common OR = 0 (95% CI 0-0.77).

CONCLUSIONS

In a setting of repeated annual mass azithromycin treatments, after approximately 80% of individuals have been located in a community, extra efforts to find absent individuals may not yield significantly more cases of ocular chlamydia.

Estimating the incidence of symptomatic rotavirus infections: a systematic review and meta-analysis

BACKGROUND

We conducted for the first time a systematic review, including a meta-analysis, of the incidence of symptomatic rotavirus (RV) infections, because (1) it was shown to be an influential factor in estimating the cost-effectiveness of RV vaccination, (2) multiple community-based studies assessed it prospectively, (3) previous studies indicated, inconclusively, it might be similar around the world.

METHODOLOGY

Pubmed (which includes Medline) was searched for surveys assessing prospectively symptomatic (diarrheal) episodes in a general population and situation, which also reported on the number of the episodes being tested RV+ and on the persons and the time period observed. A bias assessment tool was developed and used according to Cochrane guidelines by 4 researchers with different backgrounds. Heterogeneity was explored graphically and by comparing fits of study-homogenous 'fixed effects' and -heterogeneous 'random effects' models. Data were synthesized using these models. Sensitivity analysis for uncertainty regarding data abstraction, bias assessment and included studies was performed.

PRINCIPAL FINDINGS

Variability between the incidences obtained from 20 studies is unlikely to be due to study groups living in different environments (tropical versus temperate climate, slums versus middle-class suburban populations), nor due to the year the study was conducted (from 1967 to 2003). A random effects model was used to incorporate unexplained heterogeneity and resulted in a global incidence estimate of 0.31 [0.19; 0.50] symptomatic RV infections per personyear of observation for children below 2 years of age, and of 0.24 [0.17; 0.34] when excluding the extreme high value of 0.84 reported for Mayan Indians in Guatemala. Apart from the inclusion/exclusion of the latter study, results were robust.

CONCLUSIONS/SIGNIFICANCE

Rather than assumptions based on an ad-hoc selection of one or two studies, these pooled estimates (together with the measure for variability between populations) should be used as an input in future cost-effectiveness analyses of RV vaccination.

Effectiveness of childhood vaccination against rotavirus in sub-Saharan Africa: The case of Nigeria

Rotavirus diarrhoea is associated with high childhood mortality in developing countries. A new vaccine was recently licensed in Mexico. The objective of this study was to assess the effectiveness of routine childhood vaccination by this new vaccine in a developing country. We constructed a decision tree to compare two alternatives: "no vaccination programme" and "vaccination programme". The estimates used for disease incidence, vaccine efficacy and coverage rates were derived from published data. We followed a hypothetical Nigerian cohort from birth to age five. The vaccine programme would prevent 284,000 cases of rotavirus diarrhoea annually and 6129 deaths due to the disease. In this study in a sub-Saharan country, we showed that rotavirus vaccination with a new vaccine substantially reduces the number of deaths from rotavirus diarrhoea and may be of great use in developing countries.

Incentives for children in research

PURPOSE

To describe the challenges of using incentives for children in research.

ORGANIZING FRAMEWORK

A discussion of incentives in the context of recruitment for research, including a review of the literature, a description of the types of incentives used with children and their families, factors influencing choice of incentives and ethical considerations. Recommendations to guide decisions about incentives are proposed.

CONCLUSIONS

Since the 1997 mandate from the U.S. National Institutes of Health that investigators provide justification for excluding children, researchers have become more willing to include children. Whether all parts of the research process pertain to children without careful consideration and adaptation is unclear. One area lacking clarity is the use of incentives to encourage participation in research. The issue of incentives for children or parents should be considered early in the design of the research proposal, with attention to developmental age, ethical considerations, purpose of the research, and burden to the child and family.

A prospective cohort study of blood donors: methodological issues in the investigation of injuries and chronic diseases

Blood donors have made important contributions to research, most notably in cross-sectional seroprevalence studies. The proposed New Zealand Blood Donors Health Study is a prospective cohort study of 30,000 New Zealand donors designed to investigate the determinants of common injuries, cardiovascular disease and cancer. While robust from an analytic perspective, the execution of prospective cohort studies in many settings is impeded by methodological, economic and organisational barriers. We examined the operational considerations of implementing a large-scale cohort study at a transfusion centre and evaluated measures taken to optimise data collection procedures. A pilot study of 1,000 participants revealed donor motivation to participate in this research was high (91% response rate). Comprehensive exposure data on lifestyle, behavioural and psychosocial factors were obtained from 95% of participants. Substantial heterogeneity in levels of potential risk factors was noted among respondents. Detailed dietary habit information and a study blood sample were obtained from 67% and 100% of participants, respectively. Study recruitment and baseline data collection was feasible during routine donor visits with minimal interruption to donor centre staff and procedures. We conclude the study design and characteristics of the regional donor program enhance the efficiency and significance of the proposed research.

Recruitment of women into research studies: a nursing perspective

RESEARCH TRIALS HAVE historically underrepresented women, especially women of ethnic minority and lower socioeconomic groups. Although these populations of women are disproportionately afflicted with human immunodeficiency virus (HIV), HIV studies have followed this pattern of underrepresentation. Nurses working in HIV research have developed a women-centered recruitment strategy that has been successful in enrolling women in clinical trials and epidemiological studies. Reasons for women's lack of inclusion and components of a strategy to remedy the situation are discussed.