Original Article

Modifiable Risk Factors for Acute Lower Respiratory Tract Infections M.R. Savitha, S.B. Nandeeshwara, M.J. Pradeep Kumar, Farhan-ul-haque and C.K. Raju Department of Pediatrics, Government Medical College, Mysore, India [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 <0.05 in all]. Significant nutritional risk factors were administration of prelacteal feeds, early weaning, anemia, rickets and malnutrition, [p value <0.05 in all]. Significant environmental risk factors were use of kerosene lamps, biomass fuel pollution and lack of ventilation [p value <0.05 in all]. On logistic regression analysis, partial immunization, overcrowding and malnutrition were found to be significant risk factors. Conclusion. The present study has identified various socio-demographic, nutritional and environmental modifiable risk factors for ALRI which can be tackled by effective education of the community and appropriate initiatives taken by the government. [Indian J Pediatr 2007; 74 (5) : 477-482] E-mail : savvvy6 [email protected]

Key words : Acute lower respiratory tract infection; Risk factors

Children with acute respiratory infections account for 20% to 40% of the children attending outpatient clinics and 12% of these risk factors related to acquisition of ALRI will to 35% of admissions of children into hospitals. 1 It is help in its prevention, through effective health education estimated that 500 to 900 million acute respiratory of the community and appropriate initiatives taken by the infection episodes occur per year in developing government, leading to a healthy community and a countries.2 Also, about 5 million under five children die of healthy nation as a whole. The authors therefore, acute respiratory infection annually, of which 90% occur undertook this study to identify the various modifiable in developing countries.2 Acute lower respiratory tract risk factors for acute lower respiratory tract infection in infection (ALRI) is a leading cause of mortality in under under five children. five children in developing countries.3 The international consultation on control of acute respiratory infections, December 1991 reported that there are links between environmental risk factors (such as smoke, outdoor air pollution, indoor pollution, passive smoking, overcrowding) and risk factors in the child (such as low birth weight, malnutrition, measles, breast feeding and vitamin ‘A’ deficiency) with acute respiratory infections. Many of these risk factors are amenable to corrective measures. Therefore, knowledge

Correspondence and Reprint requests : Dr. M.R. Savitha, No. 79/ A,4 th Main, Maruthi Temple Road, Saraswathipuram, Mysore570 009 (Karnataka), India; Phone-0821-2341891; Mobile: 9844066497

Indian Journal of Pediatrics, Volume 74—May, 2007

MATERIALS AND METHODS The present study is a prospective case control study conducted from March 2005 to August 2005 at Cheluvamba Hospital, attached to Government Medical College, Mysore which is a teaching hospital and a referral centre. Children in the age group of 1 month to 5 yr admitted with acute lower respiratory tract infection during the study period were enrolled in the study as cases. A case of ALRI is defined as “presence of cough with fast breathing of more than 60/min in less than 2 mth of age, more than 50/min in 2 mth to 12 mth of age 477

M.R. Savitha et al and more than 40/min in 12 mth to 5 yr of age, the duration of illness being less than 30 days”. The presence of lower chest wall indrawing was taken as evidence of severe pneumonia. The presence of refusal of feeds , central cyanosis, lethargy or convulsions was taken as evidence of very severe pneumonia.4 Controls included in the study were healthy children between 1 month to 5 yr of age who were normal siblings of admitted children for non respiratory complaints during the study period. Children with a clinical diagnosis of Bronchial asthma (based on history of repeated episodes of wheeze with rapid response to bronchodilator therapy, positive family history of bronchial asthma) and children with any underlying chronic illness were excluded from the study. Verbal, informed consent of the child’s carer was obtained in both cases and controls. For both cases & controls a detailed history and physical examination was done according to a predesigned proforma to elicit various potential risk factors. Age of the child was recorded in completed months and age of parents in completed yr. A detailed history of relevant symptoms like fever, cough, rapid breathing, chest retraction, refusal of feeds, lethargy, wheezing etc., was taken. Past history of similar complaints was also taken. History of immunization was elicited from parents and verified by checking the documents wherever available. History of breastfeeding and weaning was recorded. Dietary intake of child prior to current illness was calculated by 24 hr Dietary recall method. History of upper respiratory tract infection in the family members in the preceding 2 wk was recorded. History of smoking by various family members and details of cooking fuel used was recorded. Details of the housing conditions were also obtained. Socioeconomic status grading was done according to modified kuppuswamy’s classification. A detailed examination of each child was done. Respiratory rate and heart rate were measured for one minute, when the child was quiet. A detailed anthropometry was done and malnutrition was graded according to Indian academy of Pediatrics classification. Severity of respiratory distress was assessed in each child. Anemia and other signs of vitamin deficiencies were recorded. A detailed systemic examination was done in both cases and controls. Routine hematological, urine and stool investigations were done in all cases and specific investigations were done as per requirement of individual cases.

STATISTICAL METHODS USED Chi square test was used. ‘P’ value <0.05 was taken as significant. ‘P’ value <0.001 was taken as highly significant. Logistic Regression Methods was done using SPSS version 14.0 (evaluation review). 478

RESULTS In this study 104 ALRI cases were compared with 104 normal controls. Majority of children were infants with their age distributions comparable between the two groups with male preponderance in both the groups (Table 1). When other sociodemographic variables were compared between the two groups (table 1), there were significantly higher number of illiterate mothers in cases as compared to controls (63.46% vs 19.23%) (‘p’ value <0.001). Similarly, significantly more fathers were illiterate in cases as compared to controls (59.62% vs 25%) (‘p’ value <0.001). Inappropriate immunization for age was significantly associated with ALRI (21.15% vs 7.69%) (‘p’ value<0.001). Also, Families having more than two underfive children at home, were significantly associated with ALRI (30.77% vs 11.54%) (‘p’ value<0.001). Similarly, overcrowding5 was also significantly associated with ALRI (91.35% vs 20.19%) (‘p’ value <0.001). Also, more ALRI cases were from lower and upper lower class as compared to controls (93.26% vs 62.5%) (‘p’ TABLE 1. Sociodemographic Variables in Alri Cases and Controls Variables

1. Age <1YR 1-3yr 3-5Yr 2. Sex Male Female 3. Mother’s Literacy Illiterate Primary/High school PUC Graduate 4. Father’s Literacy Illiterate Primary/High school PUC Graduate 5. Immunization Complete for age Incomplete for age 6. No. of underfive children at home <2 >2 7. Overcrowding Present Absent 8. Socioeconomic class Lower Class Upper Lower Class Lower middle class Upper Middle Class 9. Family H/o URI Infection

Alri Cases (n=104) No.[%]

Controls (n=104) No.[%]

65 [62.5%] 31 [29.8%] 8 [7.7%]

77 [74.04%] 18 [17.31%] 9 [8.65%]

67 [64.42%] 37 [35.58%]

54 [51.92%] 50 [48.08%]

66 [63.46%] 36 [34.62%] 2 [4.81%] 0

20 [19.23%] 55 [52.88%] 15 [14.42] 14 [13.46]

<0.001

62 [59.62%] 38 [36.54%] 3 [2.88%] 1 [0.96%]

26 [25%] 40 [38.46%] 23 [22.12%] 15 [14.42%]

<0.001

82 [78.85%] 22 [21.15%]

96 [92.3%] 8 [7.69%]

<0.001

72 [69.23%] 32 [30.77%]

92 [88.46%] 12 [11.54%]

<0.001

95 [91.35%] 9 [8.65%]

21 [20.19%] 83 [79.81%]

<0.001

62 [59.62%] 35 [33.65%] 6 [5.77%] 1 [0.96%]

26 [25%] 39 [37.5%] 24 [23.08%] 15 [14.42%]

<0.001

9 [8.65%)

‘P’ Value

- Nil -

Indian Journal of Pediatrics, Volume 74—May, 2007

Modifiable Risk Factors for Acute Lower Respiratory Tract Infections value<0.001). Family history of upper respiratory tract infection in the preceding two weeks was present in 8.65% cases as compared to none of the controls. Among the nutritional variables compared between cases and controls (Table 2), early weaning before 4 mth of age had a significant association with ALRI (37.5% vs 13.46%) (‘p’< 0.01). Similarly 31.73% cases had administered prelacteal feeds as compared to 3.85% of controls. Also, anemia was present in 76.92% of cases as compared to 6.73% of controls and Rickets was present in 28.85% of cases and only 3.85% of controls (p<0.01). Malnutrition was present in 83.86% of cases as compared to 2.88% of controls (p<0.01). However, there was no significant association between Vitamin A deficiency, low birth weight, and pneumonia. TABLE 2. Nutritional Variables in Alri Cases and Controls Variables

Alri Cases (n=104) No.[%]

1. Prelacteal feeds Given 33 (31.73) Not given 71 (68.27) 2. Weaning <4 months 39 (37.5) 4months-6months 44 (42.31) >6 months 21 (20.19) 3. Anemia Present 80 (76.92) Absent 24 (23.08) 4. Rickets Present 30 (28.85) Absent 74 (71.15) 5. Malnutrition Absent 45 (16.14) Gr I & II 37 (62.71) Gr III & IV 22 (21.15) 6. Birth Weight <2.5 Kg 9 (8.65) 7. Vitamin ‘A’ deficiency Present 4 (3.85)

Controls (n=104) No.[%]

‘P’ Value

4 (3.85) 100 (96.15)

<0.05

14 (13.46) 84 (80.77) 6 (5.77)

<0.01

7 (6.73) 97 (93.27)

<0.01

4 (3.85) 100 (96.15)

<0.01

101 (97.12) 3 (2.88%) - Nil -

<0.01

Variables

1. Type of Floor Mud Cow Dung Cement 2. Windows Present Absent 3. Lighting Kerosene lamps Electricity 4. Fuel used Firewood Cow dung Kerosene LPG 5. Kitchen Separate Not separate 6. Family H/o Smoking Present Absent

- Nil -

Among the environmental variables compared between cases and controls (Table 3), 61.54% of cases had either mud or cowdung flooring in their house as compared to 11.54% of controls, which was statistically significant (p<0.05). 32.7% of ALRI cases did not have any windows in their house as compared to 4.8% of controls (p<0.001). 36.54% of ALRI cases used kerosene lamps as the lighting source as compared to 2.88% of controls where electricity was the mode of lighting (p<0.001). Cooking fuel other than liquid petroleum gas was strongly associated with ALRI (98.07% in cases vs 54.8% in controls) (p<0.001). Added to this, 14.42% cases did not have a separate kitchen and they cooked their food in the living place as compared to none of the controls. Family history of smoking was seen in 73.08% of cases as compared to 36.5% of controls, however, this was not statistically significant.

Alri Cases (n=104) No.[%]

Controls (n=104) No.[%]

‘P’ Value

25 (24.04) 39 (37.5) 40 (38.46)

11 (10.58) 1 (0.96) 92 (88.46)

<0.05

70 (67.3) 34 (32.7)

99 (95.19) 5 (4.8)

<0.001

38 (36.54) 66 (63.46)

3 (2.88) 101 (97.11)

<0.001

95 (91.35) 2 (1.92) 5 (4.8) 2 (1.92)

31 (29.8) 26 (25) 47 (45.19)

<0.001

89 (85.58) 15 (14.42)

104 (100) -

76 (73.08) 28 (26.92)

38 (36.54) 66 (63.46)

>0.05

TABLE 4. Risk Factors For Acute Lower Respiratory Tract Infection Using Logistic Regression Methods Sl. Risk Factors No.

11 (10.58)

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TABLE 3. Environmental Variables in Alri Cases and Controls

1 2 3

Adjusted Odds Ratio

Partial immunization 0.006 Overcrowding 11.985 Malnutrition 6.939

95% CI

‘P’ Value

0.001-0.035 2.578-55.720 1.063-45.290

0.000 0.002 0.043

Of the 104 cases with pneumonia, 12.51% cases had pneumonia, 82.69% cases had severe pneumonia and 4.8% cases very severe pneumonia. There was past H/O pneumonia in 14.42% of cases. 5 Cases had past H/O Pneumonia in the siblings of which, 2 sibling deaths had occurred due to pneumonia. Of the 104 cases with Pneumonia 2 infants with very severe Pneumonia died. DISCUSSION The various risk factors for ALRI were broadly classified under 3 headings-sociodemographic variables, nutritional variables and environmental variables. The age and sex distributions were comparable between cases and controls. SOCIODEMOGRAPHIC VARIABLES Among the sociodemographic variables both maternal and paternal illiteracy and low socioeconomic status(SES) were significantly associated with ALRI. Similar results were found by Cunha AL et al even after adjusting for other risk factors like nutritional status and 479

M.R. Savitha et al overcrowding.6 Probably low SES leads to less access to social, human and material resources leading to more of infections. The authors also observed that partially immunized children were more prone for ALRI as compared to upto date immunized children. Similar results were found by Broor S et al.7 This is probably because mothers utilizing immunization services are better aware of health care facilities and probably seek early consultation for illness of their children, which probably avoids severe illness. Also, immunization against certain diseases like measles, H. influenza type b may protect the child against ALRI. Another significant risk factor in our study was overcrowding. Also, families with more than two children at home were more at risk for ALRI. Overcrowding contributes to the transmission of infections through respiratory droplets. Similar results were found in other studies. 2,8 A study from Brazil 9 showed that after adjustment for socioeconomic and environmental factors, the presence of three or more children under five years of age in the household was associated with a 2.5 fold increase in pneumonia mortality.

NUTRITIONAL VARIABLES The administration of prelacteal feeds and early weaning before 4 mth of age was significantly associated with ALRI in the present study. Similar results were found in other studies.7 Colostrum contains antibodies against Respiratory synctial virus and also a high concentration of C3, IgA and lactoferrin which protect against gram negative organisms. 10 In a study on ALRI specific mortality relative to breastfed infants, those, who also received artificial milk had a risk of 1.6 and non-breast fed infants, a risk of 3.6.11 Among children hospitalized with pneumonia in Rwanda, breast feeding was associated with a 50% reduction in case fatality.12 Anemia was a significant risk factor for ALRI in the present study. Not many studies have stressed on the role of anemia in ALRI. The role of anemia in infection is debated extensively. The proposed pathophysiologic basis for increased risk of infection are- neutrophils have a decreased capacity to kill staph.aureus due to decreased myeloperoxidase activity. Both the proportion and absolute number of circulating ‘T’ cells are reduced and also they have defective DNA synthesis due to decreased ribonucleotide reductase activity.13 Presence of Rickets was a significant risk factor for ALRI in the present study which was similar to other studies. 14 Humoral immunodeficiency is known in rickets, mainly in the form of dysgammaglobinemia, poor antibody response, defective opsonisation and killing.15 480

Presence of malnutrition was significantly associated with ALRI in the present study, similar to other studies.7 A study in the philippines included age stratified risks in children less than 23 mth of age and reported highest risk of death from ALRI due to malnutrition among those aged 12-22 mth.16 A study in New Delhi revealed severe malnutrition as the predictor of mortality in ALRI in 2 wk to 5 yrs old children.17 Overall malnutrition is associated with a two to three fold increase in mortality from ALRI.18 It is well known that malnourished children have defective cell mediated immunity secondary to thymolymphatic depletion leading to severe gram negative infections and sepsis. They may also have qualitatively abnormal immunoglobulin, and impairment of key enzymes involved in bactericidal action of leucocytes.19 In the present study vitamin ‘A’ deficiency was not significantly associated with ALRI. Although Vitamin ‘A’ supplements reduce overall childhood mortality in areas where deficiency is present, no reduction in ALRI morbidity or mortality has been shown.20 Environmental Variables Air pollutants increase the incidence of ALRI by adversely affecting nonspecific host defenses like filtration, mucociliary apparatus etc, and specific host defenses like cellular and humoral immunity.21 In the present study there was a significant association between mud/cow dung flooring with ALRI. Similar results were found by Sikolia et al.2 Mud floors tend to break up and cause dirt and cannot be easily washed, clear and dry and also they get dampened easily. Cracks and crevices which are common in these type of floors lead to breeding of insects and harborage of dust. In nearly 1/3rd of cases kerosene lamps were the main modes of lighting source. These are a potential source of emission of harmful particulate matter (<2.5μ) like polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, nitrated hydrocarbons etc., which as they are small, are inhaled deep into lungs, leading to greater severity of illness.22 93.2% of ALRI cases used, biomass fuels like firewood, cow dung as fuel for cooking. These biomass fuels are burnt in simple stoves with very incomplete combustion generating a lot of toxic products that adversely affect specific and nonspecific local defenses of the respiratory tract.7,21 Majority of under five children, being young spend most of their time with their mothers doing household cooking, thus getting more exposed to biomass fuel pollution. Added on to this, about 14.42% cases did not have a separate kitchen and cooking was done in the living Place, leading to bulk of emissions being released into the living area. Further, nearly 1/3rd cases did not have any windows in their house. This ill Indian Journal of Pediatrics, Volume 74—May, 2007

Modifiable Risk Factors for Acute Lower Respiratory Tract Infections ventilation further aggravated the effects of indoor pollutants. Environmental tobacco smoke (ETS) is another indoor pollutant that reduces local defense mechanisms and predisposes children to respiratory illness.8,23, 24 In the present study family history of smoking was not statistically significant. This may be because, majority of smokers in the families were fathers and the exposure of children due to smoking by fathers may be limited because of relatively greater time spent by fathers outside the house. On reanalyzing data using logistic regression methods, partial immunization, overcrowding and malnutrition remained as major independent risk factors for pneumonia. (Table 4). As children were constantly exposed to the above risk factors, 14.42% of cases also complained of past attacks of pneumonia and 5 cases had history of sibling pneumonia with 2 sibling deaths. However, the present study had certain limitations As the present study was a hospital based study, hospitalized cases may not be representative of all ALRI cases in the community. This needs an extensive population based research.25 Also the authors used a questionnaire measure to assess risk factors. This has a sensitivity of 82% and a specificity of 79% and some misclassification of the outcome may have occurred. Thirdly in view of ALRI having marked periodicity, studies on ALRI should last for at least one yr.25 The present study was done over a period of six mth.

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CONCLUSIONS The present study identified many modifiable risk factors for ALRI. The significant sociodemographic risk factors were parental illiteracy, low socioeconomic status, overcrowding and partial immunization. The significant nutritional risk factors were administration of prelacteal feeds, early weaning, anemia, rickets and malnutrition. The significant environmental risk factors were use of mud/cow dung flooring, kerosene lamps, biomass fuel pollution and lack of ventilation. On logistic regression analysis, partial immunization, overcrowding and malnutrition remained as significant independent risk factors for ALRI. The above risk factors can be tackled through effective health education of the community and appropriate initiatives taken by the government leading to a healthy community and a healthy nation as a whole. REFERENCES 1. A programme for controlling acute respiratory infections in

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