SYMPTOMATIC PLASMODIUM FALCIPARUM MALARIA FOLLOWING ADMINISTRATION OF ARTEMETHER-LUMEFANTRINE IN HEALTHY CHILDREN LIVING IN WESTERN KENYA: A TIME ANALYSIS

7/29/2019 SYMPTOMATIC PLASMODIUM FALCIPARUM MALARIA FOLLOWING ADMINISTRATION OF ARTEMETHER-LUMEFANTRINE I

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SCHOOL OF PUBLIC HEALTH

COLLEGE OF HEALTH SCIENCES

UNIVERSITY OF GHANA

SYMPTOMATIC PLASMODIUM FALCIPARUM MALARIA

FOLLOWING ADMINISTRATION OF ARTEMETHER

LUMEFANTRINE IN CHILDREN LIVING IN WESTERN

KENYA: A TIME ANALYSIS

A PROPOSAL FOR A PROJECT TO BE UNDERTAKEN IN PARTIALFULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DEGREEOF MASTERS OF SCIENCE IN CLINICAL TRIALS

BY

BEN M. ANDAGALU

SUPERVISOR: PROFESSOR FRED N. BINKA

APRIL 2010


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Table of contents

List of Abbreviations ...................................................................................................................... 3

Summary ......................................................................................................................................... 3

Introduction ..................................................................................................................................... 4

Background ................................................................................................................................. 4

Statement of problem .................................................................................................................. 5

Conceptual Framework ............................................................................................................... 6

Justification ............................................................................................................................... 10

Objectives ..................................................................................................................................... 11

Methods......................................................................................................................................... 11

Type of project .......................................................................................................................... 11

Study location ........................................................................................................................... 12

Analysis population .................................................................................................................. 12

Sample size and justification .................................................................................................... 13

Variables ................................................................................................................................... 13

Data analysis plan ..................................................................................................................... 14

Schedule of activities .................................................................................................................... 18

Budget ........................................................................................................................................... 19References ..................................................................................................................................... 20

Appendices......23Appendix 1: Epidemiology of pediatric malaria study protocolAppendix 2: Ethics committees approval lettersAppendix 3: Authorization letter from Principal InvestigatorAppendix 4: ResumAppendix 5: Sample case report form


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LIST OF ABBREVIATIONS

ACT Artemisinin-based Combination Therapy

AL Artemether-Lumefantrine

IPT Intermittent Preventive Treatment

SP Sulphadoxine-Pyrimethamine

WHO World Health Organization

SUMMARY

Intermittent Preventive Treatment (IPT) of malaria is the administration of a curative dose of an

effective antimalarial drug at pre-determined intervals to pregnant women and children, with the

primary aim of preventing malaria. Sulphadoxine-Pyrimethamine (SP) has been widely used for

IPT, but widespread resistance of Plasmodium falciparum to this drug has severely limited its

utility for IPT. New drug regimens for IPT are therefore needed to replace SP the new drugs

will have to be safe, efficacious, well tolerated and easy to administer. Since the preventive effect

of IPT is considered to work by and large via the chemoprophylactic properties of the drugs used,

it is generally recommended to use long-acting drugs for IPT. Artemether-Lumefantrine (AL) is

one of the currently recommended treatments for malaria that has proven efficacy and is very well

tolerated. While it is known to be short-acting, little is known on its actual effect on the risk for

symptomatic malaria. This proposed study intends to analyze the risk of symptomatic

Plasmodium falciparum malaria following the administration AL in healthy children, and thus

evaluate the strength of the evidence against the use short acting anti-malarial drugs for IPT. The

source of the data to be analyzed is the longitudinal cohort study of the epidemiology of pediatric

malaria that was conducted in Kombewa Division, Western Kenya between 2003 and 2004.


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INTRODUCTION

Background

Intermittent Preventive Treatment (IPT) of malaria is the administration of a curative dose of an

effective antimalarial drug at pre-determined intervals to a target population, with the primary aim

of preventing malaria. Pregnant women and children living in malaria-endemic areas are the

target of this intervention, since they are considered to be at risk of adverse outcomes of

Plasmodium. falciparum infection (Grobusch et al., 2007). IPT is one of the treatment and

prevention strategies that is recommended by WHO and is widely used in the fight against

malaria (World Health Organization, 2009). Sulphadoxine-Pyrimethamine (SP) has been widely

used for IPT, initially introduced in pregnant women, and later extended to children.

IPT has both therapeutic and protective effects (Gosling et al., 2009a). Since a therapeutic dose of

an efficacious antimalarial is used for IPT, any circulating parasites would be eliminated. This is

important, especially considering that the prevalence of asymptomatic parasitemia in some

endemic areas has been reported to be as high as 39%, and a significant proportion of these

carriers in some of the areas studied were children and pregnant women (Ogutu et al.). While such

asymptomatic carriers may not present with overt signs of clinical malaria, they are at risk for

malaria related morbidity such as anemia, which in turn, is related to poor pregnancy outcomes

and poor child health and development. In addition, these asymptomatic carriers form a reservoir

for the parasite and may serve as a source of new infections (Ogutu et al.). Thus, the therapeutic

effect serves an important public health role. The mechanism behind the protective effects of IPT

was the subject of debate in the recent past (Gosling et al., 2009a). One school of thought

attributed the effects of IPT to immune mechanisms (Schellenberg et al., 2005). In this scenario,

it was thought as the concentration of the anti-malarial drug in the blood waned over time, the


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sub-therapeutic levels thus achieved allowed the development of low-level asymptomatic

parasitemia. This in turn was thought to stimulate the development of immunity in the IPT

recipients and prevent new infections. In this case, drugs with efficacious parasite clearance and

suppressive properties would not have been considered as appropriate for IPT. Another school of

thought, however, attributed the protective effect of IPT to the chemoprophylactic properties of

the drugs used for IPT (White, 2005). In this situation, the recipient of IPT would not be

susceptible to new malaria infections for as long as adequate blood levels of the drugs were

present. Thus, the delay of the median time to first clinical episode of malaria from 38.5 days to

68 days in a study conducted in Mali was attributed to the long lasting effects of SP (Coulibaly etal., 2002). Even though the half-life of SP is approximately 7 days, chemo-suppressive levels are

maintained in the blood for as long as 60 days (Barnes et al., 2006, White, 2005). In a recent

study comparing mefloquine (a long-acting drug) and chlorproguanil-dapsone (a short-acting

drug) for IPTI, both of which are efficacious at parasite clearance, only the long-acting drug

showed protective efficacy against clinical episodes of malaria (Gosling et al., 2009b). This gives

further credence to the fact that IPT works by and large through the chemoprophylactic

mechanism. As such, it is expected that short-acting drugs should offer protective effect that

would last no longer than their half-lives and that would make them unsuitable for IPT. This

information is crucial for determining future policy regarding future alternative drug regimens for

IPT.

Statement of problem

SP was an ideal choice of drug for IPT it was highly efficacious at the time, was administered as

a single dose, thus allowing for directly observed treatment, and was generally well tolerated.

However, widespread resistance has put its utility in question. Indeed, in one IPT efficacy trial,


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the failure to demonstrate the protective efficacy of SP was attributed to resistance (Cairns et al.).

New regimens for IPT are therefore needed to replace SP. Any new regimen that will replace SP,

in addition to being efficacious in parasite clearance, will need to demonstrate protective efficacy

over and above that already offered by preventive interventions of proven efficacy that are already

in use, such as Insecticide Treated Bed-Nets (Binka et al., 1996, Nevill et al., 1996, World Health

Organization, 2009). The choice of any new regimens should also be informed by sound scientific

evidence.

Conceptual Framework

This proposed study intends to analyze the risk of symptomatic P. falciparum malaria following

the administration of Artemether-Lumefantrine, a short-acting anti-malarial drug, in healthy

children, and thus evaluate the strength of the evidence against the use short acting anti-malarial

drugs for IPT.

The source of data for this analysis will be data generated from the longitudinal cohort study of

the epidemiology of pediatric malaria that was conducted in Kombewa Division, Western Kenya

between 2003 and 2004, whose objectives were to estimate the prevalence of malaria, describe the

temporal patterns of symptomatic malaria and assess whether the administration of a curative

dose of an anti-malarial treatment at the beginning of the study leads to a large change in the

pattern of development of episodes of malaria during the follow-up period. A total of 270 initially

healthy, asymptomatic children aged between 12 months and 47 months living within the study

area were enrolled. Children who had significant pre-existing medical conditions, including

homozygous sickle-cell disease were excluded. A blood sample for the preparation of a baseline

malaria blood film was collected just before randomization the results of this slide were not

used to determine eligibility, and were not made available to the investigators. The children were


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then randomized to receive either a course of AL or placebo using a list prepared in advance using

a blocked randomization scheme. All study staff with the exception of the study pharmacists and

the study coordinator were blinded to the allocations. Each of the children was then followed up

for 1 year. The follow-up consisted of active surveillance and passive surveillance. Active

surveillance consisted of weekly visits by field workers and monthly visits at the study clinic,

during which samples for malaria blood films were collected. Blood smears were prepared, read

and verified according to standard protocols. Hemoglobin assays were run only during the

monthly visits. Results of the malaria tests from the active surveillance were not made available

to clinicians, unless the participant was unwell during a visit. Passive surveillance consisted ofunscheduled visits, when participants had specific complaints. Malaria films were done if needed

during unscheduled visits and the results made available to the attending clinician. Participants

thus diagnosed with malaria were treated with AL, regardless of their randomization group. The

study was approved by the Kenya Ethics Review Committee and the Walter Reed Army Institute

of Research Institutional Review Board, and conducted in accordance to the principles of Good

Clinical Practice. The findings of the study have not been published.

The assessment of the efficacy of any drug regimen for IPT is expected to follow the routine

methodology used for malaria preventive strategies. Endpoints that are usually assessed in

efficacy trials of malaria preventive strategies include time to first malaria episode, risk of

multiple episodes, risk of malaria-related morbidity and mortality (Moorthy et al., 2009). Several

IPT efficacy trials have reported time to first clinical malaria episode as their primary objective

(Macete et al., 2006, Massaga et al., 2003, Schellenberg et al., 2001). While this endpoint is

useful for establishing the proof of concept, public health policy makers are usually more

interested in the impact of the intervention on the burden of disease, measured in this case as the


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impact on the risk for multiple episodes of malaria in an individual. In one IPT efficacy trial

(Chandramohan et al., 2005), the risk for multiple episodes of malaria was reported as the primary

endpoint. The evaluation of these endpoints is not as straightforward as it may seem. One of the

difficulties is in the definition of clinical malaria. While most infectious diseases are diagnosed by

establishing the presence of the infective agent along with a clinical syndrome, there has been

considerable debate about the application of such criteria to define malaria in persons living in

endemic areas where asymptomatic parasitemia is a common occurrence. It has been suggested

that in the presence of a high prevalence of asymptomatic parasitemia and considering the

significant overlap of malaria symptoms with symptoms of other disease, a positive malaria testcould be an incidental finding in a sick resident of a malaria-endemic area. In this case, the

likelihood of the symptoms being attributed to malaria would depend on the level of parasitemia

the higher the level of parasitemia, the more likely it is that malaria is the cause of symptoms.

Consequently, cut-off points for levels of parasitemia above which a symptomatic person is

considered to have malaria during the conduct of efficacy trials have been estimated using

statistical methods with reference to the prevalence of asymptomatic parasitemia (Smith et al.,

1994), and some of the IPT efficacy studies used these cut-offs (Kobbe et al., 2007, May et al.,

2008). These cut-offs, however, do not exist in everyday practice any practicing healthcare

provider who encounters a sick patient with any parasitemia level regardless of whether the

prevalence of asymptomatic parasitemia in the area is high or not, will make a diagnosis of

malaria alongside any other differential diagnoses, and treat as such. Therefore the use of any

asexual parasitemia level of greater than 0 in endpoint definitions should result in higher

sensitivity of the study, more conservative results and increase the validity of the study. The other

problem area in endpoint determination is in the estimation of the risk for multiple malaria


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episodes. Usually, in studies that evaluate multiple failure events of the same type, assuming that

the events occur independently, the time at risk for the next event usually begins soon after the

subject has experienced the preceding one, that is, the risk for event number two begins as soon as

event number one has occurred. In the case of malaria, this may not be entirely true, since a

person who has been infected with malaria is not considered to be at risk for a new episode for a

particular period, and multiple malaria episodes occurring in one individual are not entirely

independent, since an individual who experiences one episode of malaria is more likely to

experience the next one. The duration of the period of no-risk is determined at least in part by

the by the pharmacokinetic properties of the antimalarial treatment used in the patient, andprobably by the biological interactions between the human immune system and the parasite. It is

expected that short-acting drugs would not influence the duration of this period significantly. In

some of the IPT trials that evaluated multiple malarial episodes, the period of no risk was

considered to be 21 days (Kobbe et al., 2007, May et al., 2008), while another used 28

days.(Dicko et al., 2008) , and yet another conducted analysis using 0 day period of no risk,

then repeated it using a 28 day period of no risk (Cairns et al., 2008). The latter study reported

more conservative findings when the 0 day period of no risk was used. The justification for or

against the use of such figures was not clearly reported by the investigators of the mentioned

studies. The choice of 28 days has been used in several non-IPT studies, probably informed by the

fact that most re-infections occur 28 days after a clinical episode as such any new episode

within this period is usually considered as recrudescence. This standpoint is supported by data

from a study that was able to differentiate new from old infections using molecular methods

(Cattamanchi et al., 2003). In addition, in order to differentiate between clinical visits for the

same malaria episode from those for a new episode at the analysis stage, the time gap is usually


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deemed necessary. The lack of independence between malaria episodes is usually handled at the

analysis stage by using the random effects Poisson regression model (D'Agostino, 2004, Rabe-

Hesketh and Everitt, 2004).

Therefore this study intends to analyze the effect of AL on time to first symptomatic P.

falciparum malaria episode, as well as its effect on the risk of multiple episodes of malaria, where

each participant will not be considered to be at risk for malaria for 28 days following each episode

of malaria.

Justification

Following reports of widespread resistance to SP, Artemisinin-based Combination Therapy

(ACT) is currently recommended as the first line treatment for uncomplicated malaria (World

Health Organization, 2010). Artemether-Lumefantrine (AL) is one of the ACTs that has been

approved and is widely used for the treatment of uncomplicated P. falciparum malaria, both in

adults and children (World Health Organization, 2010, World Health Organization, 2009). Its

efficacy, safety and tolerability in children has been demonstrated in several studies (Abdulla et

al., 2008, Adjei et al., 2009, Juma et al., 2008, von Seidlein et al., 1998). The safety of AL in

pregnant women, however, has not been fully established. It is administered as a 6-dose oral

treatment course over approximately 3 days. Despite the requirement of multiple doses, AL when

administered unsupervised (that is, given to the patient to take at home) has been shown to be as

effective as when it is administered under the direct supervision of healthcare personnel (Piola et

al., 2005). As such, AL would have been a good replacement for SP for IPT in children. However,

AL is classified as a short-acting drug the half-life of Artemether is 3.9 hours, while that of

Lumefantrine is 32.7 hours (Mwesigwa et al., White et al., 1999). Consequently, considering the

requirement that drugs for IPT should have a long half-life, AL would theoretically not be



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suitable for IPT. However, little is actually known about the effect of AL on the risk of

symptomatic malaria. It would be of interest, therefore, to evaluate the actual effect of

administration of AL in healthy children on the risk of symptomatic malaria. This information

may help inform future policy regarding IPT.

OBJECTIVES

Primary objective

To compare the time to the first symptomatic P. falciparum malaria episode in children who

received Artemether-Lumefantrine at randomization to those who received placebo.

Secondary objective

To compare the risk of multiple symptomatic P. falciparum malaria episodes in children who

received Artemether-Lumefantrine at randomization to those who received placebo over a period

of 12 months from the date of randomization.

METHODS

Type of project

This will be a data analysis project data arising from the longitudinal cohort study of the

epidemiology of pediatric malaria that was conducted in Kombewa Division, Western Kenya

between 2003 and 2004 will be used. Information about this study has been summarized in the

introduction section of this proposal, and further details are contained in the study protocolattached in the appendix.



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Study location

The original study was conducted in Kombewa, a 361 square kilometer area with year round

transmission of malaria, with the most intense transmission occurring during the long rains (April

through June) and the short rains (August through October). Anopheles gambiae is the

predominant mosquito species in this area, with an Entomologic Inoculation Rate (EIR) of 0.65

0.79. Unpublished data estimate that the monthly clinical malaria attack rates in children aged 1 to

3 years in this area ranges from 20% - 55%. The population of Kombewa is estimated to be

69382, with an under-five population of 8584. Primary outpatient health care is accessed at

community health centers that are operated by the Ministry of Health and faith basedorganizations and manned mainly by nurses. The area is also served by a district hospital having

in-patient facilities, and staffed with different cadres of government-employed healthcare

workers. The poor transportation system within the area, however, makes this facility inaccessible

to a significant proportion the area residents. The provincial referral hospital is located

approximately 30 km away from the district hospital.

During the period when the original study was conducted, malaria preventive interventions such

ITN and IPT had not been fully rolled out to most of the area. Additionally, at the time, the

Ministry of Health was yet to implement the changeover of the first line treatment for

uncomplicated malaria from SP to ACT.

Analysis population

The population for analysis will consist of children aged between 12 months and 47 months who

were enrolled into the study and randomized to the 2 treatment groups those who received AL

and those who received placebo. This analysis will be by intention-to-treat all children who

received at least 1 dose of AL or placebo at randomization will be included in the analysis.



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Sample size and justification

Assuming that 85% of children living in a malaria endemic area will experience at least 1

symptomatic malaria episode per year, a sample of 270 children will have 80% power to enable

the detection of a 30% change in the risk of the first event at a two-sided significance of=0.05.

Variables

The following baseline variables will be extracted from the study database:

Age Weight Gender Baseline parasitemia Use of bed-nets

Age, the use of bed-nets and baseline malaria parasitemia are factors that have been shown to

greatly influence the risk of development of malaria. Younger children and those who haveasymptomatic malaria parasitemia are considered at higher risk of developing symptomatic

malaria as compared to older children and those without any parasitemia respectively. Bed-nets,

on the other hand, have been shown to be protective against symptomatic malaria episodes. As

such, these variables will be considered as potential predictors of outcome in this analysis. They

will be extracted and categorized as follows:

Age group 1: 12 23 months; group 2: 24 35 months; group3: 36 47 months Bed-net use yes versus no Baseline asexual parasitemia 0 versus >0



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The following variables that will enable the determination of the analysis endpoints will be

extracted:

The date of randomization Dates of malaria blood films, both scheduled and unscheduled Results of malaria blood films Clinical findings during scheduled and unscheduled visits

Data analysis plan

Analysis of baseline characteristics

Categorical baseline variables (gender and use of bed-nets) will be summarized by presenting

their proportions by allocation group. Continuous baseline variables (age, weight and baseline

parasitemia) will be summarized by calculating the mean with standard deviation, or median with

the range, as appropriate. No formal statistical tests will be done to compare any differences in

baseline characteristics between the treatment groups.

Primary endpoint analysis

Definition of the primary endpoint

The primary endpoint will be the time to the first or only episode of symptomatic P. falciparum

malaria. Time of origin will be the date of randomization, while the time of event will be the date

of the malaria film confirming the presence of asexual forms P. falciparum in a symptomatic

child. Symptomatic P. falciparum malaria will be defined as the presence of any clinical sign of

malaria (World Health Organization, 2005) with any level of asexual P. falciparum malaria

parasite as detected by microscopy of a malaria blood film. Censoring will occur if no event has

occurred by 1 year following randomization or by the moment a participant has been lost to

follow up.



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Descriptive methods

A survival analysis of the first or only symptomatic P. falciparum malaria episode will be carried

out. The number of first or only events, together with the median and range of days to the first

event will be calculated according to the allocation groups, and further stratified by the predictor

variables. Survival function for the allocation groups will be estimated using the Kaplan-Meier

method and log rank tests performed, stratifying by the predictor variables.

Regression model

The Cox regression model will be used to estimate the hazard ratios between the allocation

groups. The influence of the predictor variables on the time to first or only event will be assessedusing the same model, and adjusted hazard ratios calculated.

Secondary endpoint analysis

Definition of the secondary endpoint

The secondary endpoint will be the risk of multiple symptomatic P. falciparum malaria episodes

occurring over a period of 12 months. The time of origin will be the date of randomization. The

time of end of observation will be 12 months from the time of origin. Censoring will occur if no

event has occurred by 12 months following randomization or by the moment a participant has

been lost to follow up. Symptomatic P. falciparum malaria will be defined as the presence of any

clinical sign of malaria (World Health Organization, 2005) with any level of asexual P.

falciparum malaria parasite as detected by microscopy of a malaria blood film. Multiple events

from each participant will be included in the analysis. The time at risk will be defined as the

period between randomization and the end of observation or censoring. Considering that

therapeutic levels of Lumefantrine, a component of AL, can persist for as long as 6 days (White et

al., 1999), and that AL is administered over 3 days, participants will not be considered to be at



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risk for symptomatic P. falciparum malaria for a period of 28 days following a symptomatic

episode.

Descriptive methods

The total number of symptomatic P. falciparum malaria episodes experienced in the allocation

groups during the observation period will be calculated. The number of events at cut-off points of

3 months and 6 months post-randomization will also be presented. The total person-time at risk

will also calculated for the cut-off points and the entire observation period, and thus event rates

calculated. All these findings will be stratified by the predictor variables.

Regression modelThe relative risks for multiple symptomatic P. falciparum malaria in the allocation groups will be

estimated using the Poisson regression model. The influence of the predictor variables on the

relative risk will be evaluated using the same model.

Significance levels

Results of analyses will be presented with 95% confidence intervals. Statistical tests will be two-

sided and run at a significance level of=0.05.

Subgroup analyses

Any subgroup analyses that may be performed will be exploratory in nature. No inferences will

be drawn from such analyses.

Missing data management

Any participant data with missing baseline information will be excluded from the analyses. For

participants who drop out or a lost to follow-up, any information contributed up to the moment of

drop out or loss to follow-up will be included in the analysis.



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Software

All statistical analyses will be run on Stata/SE 10.0 (StataCorp LP - Texas, USA)



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SCHEDULE OF ACTIVITIES



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BUDGET

Item Cost (Ghana Cedis)

Printing 200

Communication 15

Total 215



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SYMPTOMATIC PLASMODIUM FALCIPARUM MALARIA FOLLOWING ADMINISTRATION OF ARTEMETHER-LUMEFANTRINE IN HEALTHY CHILDREN LIVING IN WESTERN KENYA: A TIME ANALYSIS