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Original Article

Modifiable Risk Factors for Acute Lower RespiratoryTract Infections

M.R. Savitha, S.B. Nandeeshwara, M.J. Pradeep Kumar, Farhan-ul-haque and C.K. Raju

Department of Pediat ri cs, Government M edical Col lege, Mysore, Indi a

[Received February 23, 2006; Accepted February 15, 2007]

ABSTRACT

Objective. Acute respiratory infection is a leading cause of morbidity and mortality in under five children in developing countries.Hence, the present study was undertaken to identify various modifiable risk factors for acute lower respiratory tract infections

(ALRI) in children aged 1 mth to 5 yr.

Methods. 104 ALRI cases fulfilling WHO criteria for pneumonia, in the age group of 1 mth to 5 yr were interrogated for potential

modifiable risk factors as per a predesigned proforma. 104 healthy control children in the same age group were also interrogated.

Results. The significant sociodemographic risk factors were parental illiteracy, low socioeconomic status, overcrowding and

partial immunization, [p value

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and morethan40/minin12mthto5yrofage,thedurationofillnessbeinglessthan30days.Thepresenceoflowerchestwallindrawingwastakenasevidenceofseverepneumonia.Thepresenceofrefusaloffeeds,centralcyanosis,lethargyorconvulsionswastakenasevidenceofveryseverepneumonia.4Controlsincludedinthestudywerehealthychildrenbetween1monthto5yrofagewhowerenormalsiblingsofadmittedchildrenfornonrespiratorycomplaintsduringthestudyperiod.ChildrenwithaclinicaldiagnosisofBronchialasthma(basedonhistoryofrepeatedepisodesofwheezewithrapidresponsetobronchodilatortherapy,positivefamilyhistoryofbronchialasthma)andchildrenwithanyunderlyingchronicillnesswereexcludedfromthestudy.

Verbal,informedconsentofthechildscarerwasobtainedinbothcasesandcontrols. Forbothcases&controlsadetailedhistoryandphysicalexaminationwasdoneaccordingtoapredesignedproformatoelicitvariouspotentialriskfactors. Ageofthechildwasrecordedincompletedmonthsandageofparentsincompletedyr.Adetailedhistoryofrelevantsymptomslikefever,cough,rapidbreathing,chestretraction,refusaloffeeds,lethargy,wheezingetc.,wastaken.Pasthistoryof similar complaints was also taken. History ofimmunizationwaselicitedfromparentsandverifiedbycheckingthedocumentswhereveravailable. Historyofbreastfeedingandweaningwasrecorded. Dietaryintakeofchildpriortocurrentillnesswascalculatedby24hrDietaryrecallmethod.Historyofupperrespiratorytractinfectioninthefamilymembersinthepreceding2wkwasrecorded. Historyofsmokingbyvariousfamilymembersanddetailsofcookingfuelusedwasrecorded.Detailsofthehousingconditionswerealsoobtained.

Socioeconomicstatusgradingwasdoneaccordingtomodifiedkuppuswamysclassification.

Adetailedexaminationofeachchildwasdone.Respiratoryrateandheartrateweremeasuredforoneminute, when the chi ld was quiet . A detai ledanthropometrywasdoneandmalnutritionwasgradedaccordingtoIndianacademyofPediatricsclassification.Severityofrespiratorydistresswasassessedineachchild.Anemiaandothersignsofvitamindeficiencieswererecorded. Adetailedsystemicexaminationwasdoneinbothcasesandcontrols. Routinehematological,urineandstoolinvestigationsweredoneinallcasesandspecificinvestigationsweredoneasperrequirementof

individualcases.

STATISTICAL METHODS USED

Chisquaretestwasused.Pvalue

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value

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overcrowding.6ProbablylowSESleadstolessaccesstosocial,humanandmaterialresourcesleadingtomoreofinfections.

TheauthorsalsoobservedthatpartiallyimmunizedchildrenweremoreproneforALRIascomparedtouptodateimmunizedchildren. Similarresultswerefoundby

BroorSet al.7

Thisisprobablybecausemothersutilizingimmunizationservicesarebetterawareofhealthcarefacilitiesandprobablyseekearlyconsultationforillnessoftheirchildren,whichprobablyavoidssevereillness.Also,immunizationagainstcertaindiseaseslikemeasles,

H. influenzatypebmayprotectthechildagainstALRI.

Anothersignificantriskfactorinourstudywasovercrowding.Also,familieswith more than twochi ldren at home were more a t r isk for ALRI. Overcrowding contributes to the transmission ofinfectionsthroughrespiratorydroplets.Similarresultswerefoundinotherstudies. 2,8 AstudyfromBrazil 9

showedthatafteradjustmentforsocioeconomicand

environmentalfactors, thepresenceof threeormorechildrenunderfiveyearsofageinthehouseholdwasassociatedwitha2.5foldincreaseinpneumoniamortality.

NUTRITIONAL VARIABLES

Theadministrationofprelactealfeedsandearlyweaningbefore4mthofagewassignificantlyassociatedwithALRIinthepresentstudy.Similarresultswerefoundinotherstudies.7ColostrumcontainsantibodiesagainstRespiratorysynctialvirusandalsoahighconcentration

ofC3,IgAandlactoferrinwhichprotectagainstgramnegativeorganisms.10InastudyonALRIspecificmortalityrelativetobreastfedinfants,those,whoalsoreceivedartificialmilkhadariskof1.6andnonbreastfedinfants,ariskof3.6.11Amongchildrenhospitalizedwith pneumonia in Rwanda, breast feeding wasassociatedwitha50%reductionincasefatality. 12

AnemiawasasignificantriskfactorforALRIinthepresentstudy. NotmanystudieshavestressedontheroleofanemiainALRI.Theroleofanemiaininfectionisdebatedextensively.Theproposedpathophysiologicbasisforincreasedriskofinfectionareneutrophilshaveadecreasedcapacitytokillstaph.aureusduetodecreased

myeloperoxidaseactivity.BoththeproportionandabsolutenumberofcirculatingTcellsarereducedandalsotheyhavedefectiveDNAsynthesisduetodecreasedribonucleotidereductaseactivity.13

PresenceofRicketswasasignificantriskfactorforALRIinthepresentstudywhichwassimilartootherstudies.14Humoralimmunodeficiencyisknowninrickets,mainlyintheformofdysgammaglobinemia,poorantibodyresponse,defectiveopsonisationandkilling.15

PresenceofmalnutritionwassignificantlyassociatedwithALRIinthepresentstudy,similartootherstudies.7

Astudyinthephilippinesincludedagestratifiedrisksinchildrenlessthan23mthofageandreportedhighestriskofdeathfromALRIduetomalnutritionamongthoseaged1222mth.16

AstudyinNewDelhirevealedseveremalnutritionasthepredictorofmortalityinALRIin2wkto5yrsoldchildren.17OverallmalnutritionisassociatedwithatwotothreefoldincreaseinmortalityfromALRI. 18Itiswellknownthatmalnourishedchildrenhavedefectivecellmediatedimmunitysecondarytothymolymphaticdepletionleadingtoseveregramnegativeinfectionsandsepsis.Theymayalsohavequalitativelyabnormalimmunoglobulin,andimpairmentofkeyenzymesinvolvedinbactericidalactionofleucocytes.19

InthepresentstudyvitaminAdeficiencywasnotsignificantlyassociatedwithALRI. AlthoughVitaminAsupplementsreduceoverallchildhoodmortalityin

areaswheredeficiencyispresent,noreductioninALRImorbidityormortalityhasbeenshown.20

Environmental Variables

Air pollutantsincrease the incidenceof ALRI byadverselyaffectingnonspecifichostdefenseslikefiltration,mucociliaryapparatusetc,andspecifichostdefenseslikecellularandhumoralimmunity.21

Inthepresentstudytherewasasignificantassociationbetweenmud/cowdungflooringwithALRI. SimilarresultswerefoundbySikoliaet al.2Mudfloorstendtobreakupandcausedirt andcannotbeeasilywashed,clearanddryandalsotheygetdampenedeasily.Cracks

andcreviceswhicharecommoninthesetypeoffloorsleadtobreedingofinsectsandharborageofdust.

Innearly1/3rdofcaseskerosenelampswerethemainmodesoflightingsource. Theseareapotentialsourceofemissionofharmfulparticulatematter(

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ventilationfurtheraggravatedtheeffectsofindoorpollutants.

Environmentaltobaccosmoke(ETS)isanotherindoorpollutantthatreduceslocaldefensemechanismsandpredisposeschildrentorespiratoryillness.8,23,24Inthepresentstudy family history of smoking was not

statisticallysignificant. Thismaybebecause,majorityofsmokersinthefamilieswerefathersandtheexposureofchildrenduetosmokingbyfathersmaybelimitedbecauseofrelativelygreatertimespentbyfathersoutsidethehouse.

Onreanalyzingdatausinglogisticregressionmethods,partialimmunization,overcrowdingandmalnutritionremained as major independent risk factors forpneumonia.(Table4).

Aschildrenwereconstantlyexposedtotheaboveriskfactors,14.42%ofcasesalsocomplainedofpastattacksofpneumoniaand5caseshadhistoryofsiblingpneumoniawith2siblingdeaths.

However,thepresentstudyhadcertainlimitations-

Asthepresentstudywasahospitalbasedstudy,hospitalizedcasesmaynotberepresentativeofallALRIcases in the community.This needs an extensivepopulationbasedresearch. 25Alsotheauthorsusedaquestionnairemeasuretoassessriskfactors.Thishasasensitivityof82%andaspecificityof79%andsomemisclassificationoftheoutcomemayhaveoccurred.ThirdlyinviewofALRIhavingmarkedperiodicity,studiesonALRIshouldlastforatleastoneyr.25Thepresentstudywasdoneoveraperiodofsixmth.

CONCLUSIONS

ThepresentstudyidentifiedmanymodifiableriskfactorsforALRI.Thesignificantsociodemographicriskfactorswereparentalilliteracy,lowsocioeconomicstatus,overcrowdingandpartialimmunization.Thesignificantnutritionalriskfactorswereadministrationofprelactealfeeds,earlyweaning,anemia,ricketsandmalnutrition.Thesignificantenvironmentalriskfactorswereuseofmud/cowdungflooring,kerosenelamps,biomassfuelpollutionandlackofventilation.Onlogisticregressionanalysis,partialimmunization,overcrowdingandmalnutritionremainedassignificantindependentrisk

factorsforALRI.

Theaboveriskfactorscanbetackledthrougheffectivehealtheducationofthecommunityandappropriateinitiativestakenbythegovernmentleadingtoahealthycommunityandahealthynationasawhole.

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