New results for intermittent preventative therapy in children

Truly beautiful studies – well designed, well thought, even examined cost and service delivery – were recently conducted for regular, presumptive antimalarial treatment (using SP and amodiaquine) of children in Mali and Burkina Faso in settings where treated bed-nets are already in use (PLoS Medicine – open access!). The intervention was effective at reducing clinical burden – from malaria incidence, the primary target, to secondary endpoints such as anemia, all-cause mortality, and stunting.

There is one important caveat here – IPTc is only “effective” where the transmission is quite high. In the communities in Burkina Faso and Mali where the study was conducted transmission was  very intense (3-13 infective mosquito bites per person per month). At medium and low levels of transmission (last two rows of the table) the strategy becomes rather untenable, expending a lot of drug (which wastes money and risks side effects and resistance), for preventing a single case. Caveat to my caveat – the interpretation of rates differences in number needed to treat calculations is not always straightforward though I believe valid in this case.

Table: Number need to treat (NNT) and post-intervention incidence rate across varying baseline transmission and IPTc efficacy

IPTc Efficacy

85%

75%

65%

Baseline*

Rate

NNT

Rate

NNT

Rate

NNT

1000.0

150.0

0.1

250.0

0.1

350.0

0.2

100.0

15.0

1.2

25.0

1.3

35.0

1.5

10.0

1.5

11.8

2.5

13.3

3.5

15.4

1.0

0.2

117.6

0.3

133.3

0.4

153.8

0.1

0.0

1176.5

0.0

1333.3

0.0

1538.5

*Baseline transmission and rates with the intervention are expressed per 100 persons per season

Interestingly, similar to the famous Garki project the reductions in incidence appear to be much greater than reductions in prevalence – likely due to the seasonal nature of the intervention against a high vectorial capacity and thus risk of exposure.  Since the focus here is burden reduction, and not transmission reduction as in Garki, it doesn’t matter though.

Advertisements

Archives


%d bloggers like this: