***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Anaemic status is determined by haemoglobin using the HemoCue system or haematocrit measurements , and a threefold conversion is commonly used to equate the two measures ( haemoglobin = haematocrit/3 ) . The validity of this conversion in malaria endemic setting s was assessed . Methods Concurrent measures of haemoglobin and centrifuged haematocrit in children aged 6–59 months were compared by modelling the difference between the two measures against their average . A r and om effects linear regression of the difference of the measures on their average was used to describe the line of best agreement and 95 % limits of agreement for these two measures over a range of values after adjusting for statistically significant covariates . Results There was a consistent bias between the two measures , with haemoglobin less than haematocrit/3 in 87 % ( 899/1,030 ) of observations . This difference was non-uniform , decreasing with the average measure , i.e. less difference at higher haemoglobin and haematocrit values . In these studies , use of haematocrit would have underestimated the prevalence of anaemia by misclassifying 10 % ( 89/920 ) of individuals with haemoglobin < 11 g/dl , 66 % ( 252/380 ) of individuals with haemoglobin < 8 g/dl and 100 % ( 23/23 ) of individuals with haemoglobin < 5 g/dl . The mean difference between the measures was greater in males than females , increased with age between 6–59 months , and was greater in the wet than dry season suggesting that the relationship between haemoglobin and haematocrit may be modified by exposure to malaria . Conclusion The regression model indicated that the st and ard threefold conversion from haematocrit to haemoglobin underestimates the prevalence of haemoglobin < 11 g/dl in children under five years of age in malaria endemic setting s. This bias was more acute for more severe anaemia defined by haemoglobin < 8 g/dl and haemoglobin < 5 g/dl . This has important implication s for the comparability of studies using these different measures . Direct determination of haemoglobin should be the measurement of choice for assessing anaemia outcomes in malaria intervention trials and surveys BACKGROUND The published literature on cluster r and omized trials focuses on outcomes that are either continuous or binary . In many trials , the outcome is an incidence rate , such as mortality , based on person-years data . In this paper we review methods for the analysis of such data in cluster r and omized trials and present some simple approaches . METHODS We discuss the choice of the measure of intervention effect and present methods for confidence interval estimation and hypothesis testing which are conceptually simple and easy to perform using st and ard statistical software . The method proposed for hypothesis testing applies a t-test to cluster observations . To control confounding , a Poisson regression model is fitted to the data incorporating all covariates except intervention status , and the analysis is carried out on the residuals from this model . The methods are presented for unpaired data , and extensions to paired or stratified clusters are outlined . RESULTS The methods are evaluated by simulation and illustrated by application to data from a trial of the effect of insecticide-impregnated bednets on child mortality .  CONCLUSIONS The techniques provide a straightforward approach to the analysis of incidence rates in cluster r and omized trials . Both the unadjusted analysis and the analysis adjusting for confounders are shown to be robust , even for very small numbers of clusters , in situations that are likely to arise in r and omized trials A project testing the efficacy of insecticide (permethrin)-impregnated bed nets , compared with impregnated door and window curtains , residual house spraying , and a control group was implemented in 12 village clusters in the Nsukka Local Government Area of Enugu State , Nigeria , using epidemiologic and entomologic indicators . The appropriate material s and services were given free to all families . During the first year of study , three monitoring exercises were carried out in a r and om selection of homes where children under 5 years of age resided . Information was collected on perceived effectiveness of the interventions , condition of nets and curtains , reasons for not sleeping under nets , and recall of steps required in caring for nets and curtains . Bed nets were perceived as more effective in reducing mosquito bites compared with the two other interventions . At the last monitoring period , which occurred a few weeks before a re-impregnation exercise , respondents also perceived bed nets to be most effective in preventing malaria . These findings coincided with epidemiologic evidence . Curtains , especially those at doors , were more likely to be torn and dirty than bed nets . Although holes would not reduce the effectiveness of the insecticide , they could reduce the ' beauty ' of the curtains , a perceived benefit that initially attracted villagers to both curtains and nets . Bed net owners reported significantly less frequent use of other mosquito control measures in their homes than did members of the other groups . Finally , bed net users demonstrated increased knowledge of use and care steps than did those with curtains . These findings suggested a high level of social acceptability of bed nets , and point to the need to test their acceptability further under conditions where people would pay for nets and communities would manage distribution and re-impregnation systems Trials were undertaken in a hypoendemic area of malaria in an area bordering Vietnam , in Napo County of Guangxi Zhuang Autonomous Region , China . The aim was to compare the relative cost effectiveness of DDT residual spraying and of bednets impregnated with deltamethrin in the malaria control program . The trials were divided into three subgroups : ( 1 ) two farming areas and one coal mining area with a total population > 20,000 , where the trial consisted of mass bednets impregnated with deltamethrin 15 mg/m2 net surface once a year , ( 2 ) one farming area with a population of approximately 3,600 where  DDT residual spraying at 2g/m2 was carried out twice a year in May and August ; ( 3 ) one farming area and one coal mining village with a population of > 4,000 were used as a control . The malaria vector population consisted mainly of Anopheles minimus and An . anthropophagus with a small contribution from An . sinensis . After bednets were impregnated with deltamethrin  the mosquitos resting on the surface of the bednets decreased significantly , although there was less effect on the total vector population . The results showed that malaria incidence decreased significantly both in areas where impregnated bednets were used and in areas where residual spraying was undertaken . The positive IFAT rates of residents who slept under impregnated bednets decreased significantly in farming areas , especially in that area where bednet impregnation as a vector control measure had been undertaken for two years , but there was no change in the IFAT rate in DDT sprayed or control areas . ( ABSTRACT TRUNCATED AT 250 WORDS This study from two districts of Orissa State which are endemic for Plasmodium falciparum transmitted by Anopheles fluviatilis and A. culicifacies investigated the impact of dichlorodiphenyl trichloroethane ( DDT ) indoor residual spraying , in view of the ongoing discussion on phasing out DDT in India . Based on their high annual parasite incidence and logistical considerations , 26 villages in Malkangiri and 28 in Koraput district were selected for DDT spraying .  For comparison , six and four unsprayed villages were chosen from the same districts . In each district , the prevalence of malaria infection and incidence of malaria fever , indoor resting density and parous rate of the vectors , and their susceptibility to DDT were monitored in six and three villages selected r and omly from the sprayed and unsprayed groups respectively . Anopheles fluviatilis was susceptible to DDT while A. culicifacies was resistant . DDT residual spraying with 1 g/m(2 ) , was carried out in October-November 2001 . Spraying 74 - 86 % of human dwellings and 100 % of cattle sheds brought down the indoor resting density of A. fluviatilis by 93 - 95 % . This was associated with a significant reduction of incidence of malaria fever as well as prevalence of malaria infection from November to February in both districts . The spraying also seemed to impact on vector longevity , and a residual effect of DDT on the sprayed walls was observed up to 10 - 12 weeks despite re-plastering . Hence DDT spraying can still be an effective tool for controlling fluviatilis-transmitted malaria . Although this species is exophilic , its nocturnal resting behaviour facilitates its contact with the sprayed surfaces . DDT is still useful for residual spraying in India , particularly in areas where the vectors are endophilic and not resistant We conducted a community-r and omized controlled trial in Pakistan to determine the efficacy of indoor residual spraying with alphacypermethrin ( ' Fendona ' , Cyanamid , NJ , USA ) , applied at 25 mg/m2 , to prevent falciparum and vivax malaria . Wettable powder ( WP ) and suspension concentrate ( SC ) formulations were tested against an unsprayed control in an irrigated rice-growing area of Sheikhupura district , Punjab province . The study area of 180 km2 was divided into nine sectors , which were assigned at r and om to control , WP , or SC treatments in replicates of 3 . Sentinel villages were selected from each sector for entomological and disease monitoring . Malaria was monitored by fortnightly active case detection ( ACD ) and by cross- sectional parasite surveys on schoolchildren . Mosquito population s were monitored by space spraying of rooms and by cattle-l and ing catches . The spray campaign took place in June 1997 and covered 96 % of compounds . During the 7 months after spraying , the incidence of falciparum malaria was 95 % lower and that of vivax malaria 80 % lower in WP-sprayed than unsprayed sectors . Similar results were obtained for sectors sprayed with the SC formulation . Cross-sectional surveys gave estimates of efficacy comparable to those obtained by ACD . Anopheles culicifacies was 80 % less abundant and A.stephensi , the predominant anopheline , was up to 68 % less abundant in sprayed areas over the 7-month period . Reductions in anopheline parous rates indicated that the single-spray treatment was effective for the entire transmission season . Sprayed surfaces lacked odour , which contributed to the popularity of the campaign . Alphacypermethrin is a promising insecticide for the control of malaria in Pakistan and South Asia generally This study compares the effectiveness and cost-effectiveness of indoor residual house-spraying ( IRS ) and insecticide-treated bednets ( ITNs ) against infection with Plasmodium falciparum as part of malaria control in the highl and s of western Kenya . Homesteads operationally targeted for IRS and ITNs during a district-based emergency response undertaken by an international relief agency were selected at r and om for evaluation . Five hundred and ninety homesteads were selected ( 200 with no vector control , 200 with IRS and 190 with ITNs ) . In July 2000 , residents in these homesteads were r and omly sample d according to three age-groups : 6 months-4 years , 5 - 15 years , and > 15 years for the presence of P. falciparum antigen ( Pf HRP-2 ) using the rapid whole blood immunochromatographic test ( ICT ) . The prevalence of P. falciparum infection amongst household members not protected by either IRS or ITN was 13 % . Sleeping under a treated bednet  reduced the risk of infection by 63 % ( 58 - 68 % ) and sleeping in a room sprayed with insecticide reduced the risk by 75 % ( 73 - 76 % ) . The economic cost per infection case prevented by IRS was US$ 9 compared to US$ 29 for ITNs . This study suggests that IRS may be both more effective and cheaper than ITNs in communities subjected to low , seasonal risks of infection and as such should be considered as part of the control armamentarium for malaria prevention Malaria is one of the leading causes of morbidity and mortality in the developing world and a major public health problem in India . Disillusioned by in-house residual spraying ( IRS ) , and increasingly aware that insecticide-treated nets ( ITNs ) have proved to be effective in reducing malaria mortality and morbidity in various epidemiological setting s , policy-makers in India are keen to identify which is the more cost-effective malaria control intervention . A community r and omised controlled trial was set up in Surat to compare the effectiveness and efficiency of IRS and ITNs . Both control strategies were shown to be effective in preventing malaria over the base-case scenario of early diagnosis and prompt treatment . The mean costs per case averted for ITNs was statistically significantly lower ( Rs . 1848 , 1567 - 2209 ; US$ 52 ) than IRS ( Rs . 3121 , 2386 - 4177 , US$ 87 ) . The incremental cost-effectiveness ratio for ITNs over IRS was Rs . 799 ( US$ 22 ) . The conclusions were robust to changes in assumptions . This study exp and s the scope of recent comparative economic evaluations of ITNs and IRS , since it was carried out in a low mortality malaria endemic area In an intensely malarious area in north-east Tanzania , microencapsulated lambdacyhalothrin was used in four villages for treatment of bednets ( provided free of charge ) and in another four villages the same insecticide was used for house spraying . Another four villages received neither intervention until the end of the trial but were monitored as controls . Bioass 
    Output:
    
Historical and programme documentation has clearly established the impact of IRS .
However , the number of high- quality trials are too few to quantify the size of effect in different transmission setting s. The evidence from r and omized comparisons of IRS versus no IRS confirms that IRS reduces malaria incidence in unstable malaria setting s , but r and omized trial data from stable malaria setting s is very limited .