The choice of reference chart affects the strength of the association between malaria in pregnancy and small for gestational age: an individual participant data meta-analysis comparing the Intergrowth-21 with a Tanzanian birthweight chart

BACKGROUND

The prevalence of small for gestational age (SGA) may vary depending on the chosen weight-for-gestational-age reference chart. An individual participant data meta-analysis was conducted to assess the implications of using a local reference (STOPPAM) instead of a universal reference (Intergrowth-21) on the association between malaria in pregnancy and SGA.

METHODS

Individual participant data of 6,236 newborns were pooled from seven conveniently identified studies conducted in Tanzania and Malawi from 2003-2018 with data on malaria in pregnancy, birthweight, and ultrasound estimated gestational age. Mixed-effects regression models were used to compare the association between malaria in pregnancy and SGA when using the STOPPAM and the Intergrowth-21 references, respectively.

RESULTS

The 10th percentile for birthweights-for-gestational age was lower for STOPPAM than for Intergrowth-21, leading to a prevalence of SGA_STOPPAM of 14.2% and SGA_IG21 of 18.0%, p < 0.001. The association between malaria in pregnancy and SGA was stronger for STOPPAM (adjusted odds ratio (aOR) 1.30 [1.09-1.56], p < 0.01) than for Intergrowth-21 (aOR 1.19 [1.00-1.40], p = 0.04), particularly among paucigravidae (SGA_STOPPAM aOR 1.36 [1.09-1.71], p < 0.01 vs SGA_IG21 aOR 1.21 [0.97-1.50], p = 0.08).

CONCLUSIONS

The prevalence of SGA may be overestimated and the impact of malaria in pregnancy underestimated when using Intergrowth-21. Comparing local reference charts to global references when assessing and interpreting the impact of malaria in pregnancy may be appropriate.

Weight change during the first week of life and a new method for retrospective prediction of birthweight among exclusively breastfed newborns

INTRODUCTION

Identification of low birthweight and small for gestational age is pivotal in clinical management and many research studies, but in low-income countries, birthweight is often unavailable within 24 h of birth. Newborn weights measured within days after birth and knowledge of the growth patterns in the first week of life can help estimate the weight at birth retrospectively. This study aimed to generate sex-specific prediction maps and weight reference charts for the retrospective estimation of birthweight for exclusively breastfed newborns in a low-resource setting.

MATERIAL AND METHODS

This was a prospective cohort study nested in a clinical trial of intermittent preventive treatment in pregnancy for malaria with either dihydroartemisinin-piperaquine with/without azithromycin or sulfadoxine-pyrimethamine in Korogwe District, north-eastern Tanzania (Clinicaltrials.gov: NCT03208179). Newborns were weighed at birth or in the immediate hours after birth and then daily for 1 week. Reference charts, nadir, time to regain weight, and prediction maps were generated using nonlinear mixed-effects models fitted to the longitudinal data, incorporating interindividual variation as random effects. Predictions and prediction standard deviations were computed using a linear approximation approach.

RESULTS

Between March and December 2019, 513 live newborns with birthweights measured within 24 h of delivery were weighed daily for 1 week. Complete datasets were available from 476 exclusively breastfed newborns. There was a rapid decline in weight shortly after delivery. The average weight loss, time of nadir, and time to regain weight were 4.3% (95% confidence interval [CI] 3.8-4.9) at 27 h (95% CI 24-30) and 105 h (95% CI 91-120) in boys and 4.9% (95% CI 4.2-5.6) at 28 h (95% CI 23-33) and 114 h (95% CI 93-136) in girls, respectively. The data were used to generate prediction maps with 1-h time intervals and 0.05 kg weight increments showing the predicted birthweights and weight-for-age and weight-change-for-age reference charts depicting variation in weight loss from <1 to >10%.

CONCLUSIONS

The prediction maps and reference charts can be used by researchers in low-resource settings to retrospectively estimate birthweights using weights collected up to 168 h after delivery, thereby maximizing data utilization. Clinical practitioners can also use the prediction maps to retrospectively classify newborns as low birthweight or small for gestational age.

Pattern of all-causes and cause-specific mortality in an area with progressively declining malaria burden in Korogwe district, north-eastern Tanzania

BACKGROUND

Although death records are useful for planning and monitoring health interventions, such information is limited in most developing countries. Verbal autopsy (VA) interviews are alternatively used to determine causes of death in places without or with incomplete hospital records. This study was conducted to determine all causes and cause-specific mortality in Korogwe health and demographic surveillance system (HDSS) undertaken in Korogwe district, northeastern Tanzania.

METHODS

The study was conducted from January 2006 to December 2012 in 14 villages under Korogwe HDSS. Vital events such as births, deaths and migrations were routinely updated quarterly. A standard VA questionnaire was administered to parents/close relatives of the deceased to determine cause of death.

RESULTS

Overall, 1325 deaths of individuals with median age of 46 years were recorded in a population with 170,471.4 person years observed (PY). Crude mortality rate was 7.8 per 1000 PY (95% CI 7.2-8.4) and the highest rate was observed in infants (77.9 per 1000 PY; 95% CI 67.4-90.0). The overall mortality increased between 2006 and 2007, followed by a slight decline up to 2011, with the highest decrease observed in 2012. Causes of deaths were established in 942 (71.1%) deaths and malaria (198 deaths, 21.0%) was the leading cause of death in all age groups except adults (15-59 years). HIV/AIDS (17.6%, n = 365) was the leading cause of death in individuals aged 15-59 years followed by malaria (13.9%) and tuberculosis. Non-communicable diseases (NCDs) including stroke, hypertension, cancer, and cardiac failure caused majority of deaths in elderly (60 years and above) accounting for 37.1% (n = 348) of all deaths, although malaria was the single leading cause of death in this group (16.6%).

CONCLUSION

The study showed a significant decline of deaths in the Korogwe HDSS site and malaria was the main cause of death in all age groups (except adults, aged 15-59 years) while HIV/AIDS and NCDs were the main causes in adults and elderly, respectively. Further surveillance is required to monitor and document changes in cause-specific mortality as malaria transmission continues to decline in this and other parts of Tanzania.

A phase 3 trial of RTS,S/AS01 malaria vaccine in African infants

BACKGROUND

The candidate malaria vaccine RTS,S/AS01 reduced episodes of both clinical and severe malaria in children 5 to 17 months of age by approximately 50% in an ongoing phase 3 trial. We studied infants 6 to 12 weeks of age recruited for the same trial.

METHODS

We administered RTS,S/AS01 or a comparator vaccine to 6537 infants who were 6 to 12 weeks of age at the time of the first vaccination in conjunction with Expanded Program on Immunization (EPI) vaccines in a three-dose monthly schedule. Vaccine efficacy against the first or only episode of clinical malaria during the 12 months after vaccination, a coprimary end point, was analyzed with the use of Cox regression. Vaccine efficacy against all malaria episodes, vaccine efficacy against severe malaria, safety, and immunogenicity were also assessed.

RESULTS

The incidence of the first or only episode of clinical malaria in the intention-to-treat population during the 14 months after the first dose of vaccine was 0.31 per person-year in the RTS,S/AS01 group and 0.40 per person-year in the control group, for a vaccine efficacy of 30.1% (95% confidence interval [CI], 23.6 to 36.1). Vaccine efficacy in the per-protocol population was 31.3% (97.5% CI, 23.6 to 38.3). Vaccine efficacy against severe malaria was 26.0% (95% CI, -7.4 to 48.6) in the intention-to-treat population and 36.6% (95% CI, 4.6 to 57.7) in the per-protocol population. Serious adverse events occurred with a similar frequency in the two study groups. One month after administration of the third dose of RTS,S/AS01, 99.7% of children were positive for anti-circumsporozoite antibodies, with a geometric mean titer of 209 EU per milliliter (95% CI, 197 to 222).

CONCLUSIONS

The RTS,S/AS01 vaccine coadministered with EPI vaccines provided modest protection against both clinical and severe malaria in young infants. (Funded by GlaxoSmithKline Biologicals and the PATH Malaria Vaccine Initiative; RTS,S ClinicalTrials.gov number, NCT00866619.).

First results of phase 3 trial of RTS,S/AS01 malaria vaccine in African children

BACKGROUND

An ongoing phase 3 study of the efficacy, safety, and immunogenicity of candidate malaria vaccine RTS,S/AS01 is being conducted in seven African countries.

METHODS

From March 2009 through January 2011, we enrolled 15,460 children in two age categories--6 to 12 weeks of age and 5 to 17 months of age--for vaccination with either RTS,S/AS01 or a non-malaria comparator vaccine. The primary end point of the analysis was vaccine efficacy against clinical malaria during the 12 months after vaccination in the first 6000 children 5 to 17 months of age at enrollment who received all three doses of vaccine according to protocol. After 250 children had an episode of severe malaria, we evaluated vaccine efficacy against severe malaria in both age categories.

RESULTS

In the 14 months after the first dose of vaccine, the incidence of first episodes of clinical malaria in the first 6000 children in the older age category was 0.32 episodes per person-year in the RTS,S/AS01 group and 0.55 episodes per person-year in the control group, for an efficacy of 50.4% (95% confidence interval [CI], 45.8 to 54.6) in the intention-to-treat population and 55.8% (97.5% CI, 50.6 to 60.4) in the per-protocol population. Vaccine efficacy against severe malaria was 45.1% (95% CI, 23.8 to 60.5) in the intention-to-treat population and 47.3% (95% CI, 22.4 to 64.2) in the per-protocol population. Vaccine efficacy against severe malaria in the combined age categories was 34.8% (95% CI, 16.2 to 49.2) in the per-protocol population during an average follow-up of 11 months. Serious adverse events occurred with a similar frequency in the two study groups. Among children in the older age category, the rate of generalized convulsive seizures after RTS,S/AS01 vaccination was 1.04 per 1000 doses (95% CI, 0.62 to 1.64).

CONCLUSIONS

The RTS,S/AS01 vaccine provided protection against both clinical and severe malaria in African children. (Funded by GlaxoSmithKline Biologicals and the PATH Malaria Vaccine Initiative; RTS,S ClinicalTrials.gov number, NCT00866619 .).