Abstract

This study was conducted to determine the prevalence of rheumatic heart disease (RHD) and congenital heart disease (CHD) in primary schoolchildren of Menoufia, Egypt and to study the relationship between these two problems and socioeconomic conditions. A total of 8000 children were screened for cardiac disease in their schools. Children with confirmed RHD and CHD in addition to 200 healthy children (controls) were visited at their homes to assess their social environment and other factors according to a designed questionnaire. We found prevalence rates of 3.4/1000 and 2.6/1000 for the RHD and CHD respectively. The most common cardiac defects were double mitral and pulmonary stenosis in the RHD and CHD groups respectively. Nineteen (39.6%) of the patients were diagnosed for the first time during the study. Penicillin prophylaxis was received by only four (14.8%) of the RHD children and none of the CHD children. The number of other affected siblings, increased multiparity, repeated abortion, and intake of contraceptives by mothers were significantly higher in families of the children with CHD. The proportion of illiterate, unskilled, and heavy smoking fathers was higher in the two patient groups. Family income was lowest in the RHD group, while increased crowding index and low whole social environment were significantly related to both RHD and CHD. Effective programs at the community and health service levels are needed in Menoufia to solve the problem of heart disease in schoolchildren in the immediate future.

Ann Saudi Med 1994,14(3): 225-229.

Subjects and Methods

Menoufia governate lies 75 km from Cairo, Egypt with a population of approximately two million, the majority of whom are farmers and workers, and is divided into five urban-rural areas. Out of the 200,000 children attending compulsory primary schools in the governate, 8000 were chosen in this study by proportionate allocation method.¹¹ These 8000 children represented all the children registered in 14 schools, which were selected based on their population size to provide the sample size required and to represent the five areas of the governate. This study was conducted from September 1990 to April 1991 and consisted of clinical and epidemiological surveys.

Clinical Survey

In this part, the selected schools were visited by a team consisting of three pediatricians. All children attending on the visit day were examined by members of the team who focused on cardiac examination. Children judged by at least two examiners to have established or suspected heart disease were referred to the Menoufia University Hospital. Further, children registered in the school as having heart disease, who were absent on the visit day, were left a referral note to go to the hospital. In the hospital, children were subjected to detailed history obtained from the parents as well as examination by a pediatric cardiologist and to the following investigations: chest x-ray, electrocardiogram, echocardiogram (M-mode and 2D) and color Doppler (CW, PW, CD, CFM, HP-Sono 500, USA). According to history, physical examination, and investigation, children with innocent murmur and those who proved to be free from heart disease were excluded from the study and those with confirmed heart disease were classified into congenital heart disease (CHD) (Group 1) and rheumatic heart disease (RHD) (Group 2). The diagnosis in the first group was based on a history of illness since early infancy in the majority of cases, on murmur characteristics, x-ray and echocardiogram findings. RHD was diagnosed based on previous history of rheumatic fever, when reported, multiplicity and nature of valvular cardiac defects, and echocardiographic findings. Children in this group were further subjected to determination of erythrocyte sedimentation rate, anti-streptolysin-0 titer, and C-reactive protein to rule out possible recent rheumatic activity.

Epidemiological Survey

In the second part of the study, all children with documented heart disease were visited at their homes by two members of the team. Two hundred healthy children, chosen by simple random sampling from the study schools, were included in this part as the control group (Group 3). Randomization of this group was proportional to the number of diseased children in each school. The purpose of home visits was to assess the socioeconomic conditions of all the children according to a scoring system¹¹ derived from a designed questionnaire inquiring about extra and intrafamilial data.

Statistical Analysis

The three groups were compared regarding the scores of their clinical and socioeconomic data using frequency tables, t-test, X, F and Z tests where applicable. A P value <0.05 was considered significant.

Results

A total of 8000 children (4150 males and 3850 females, six to 12 years of age) were screened for cardiac abnormalities in their schools. Out of 281 children referred to the hospital, 167 were diagnosed as having innocent murmur and 66 proved to be free from cardiac problems (39 and 27 were initially suspected as having RHD and CHD respectively) and were excluded from the study. RHD was diagnosed in 27 children and CHD was detected in 21 children, making prevalence rates of 3.4/1000 and 2.6/1000 respectively (Table 1). Older children (10 to 12 years) had higher RHD prevalence than younger ones while CHD was detected in female more than male children. None of the RHD children showed clinical or laboratory evidence of rheumatic activity and none of the children in either group were suffering from any acute complications at the time of the study.

The most common cardiac lesion detected in the RHD group was double mitral (DM) followed by isolated mitral regurgitation (MR), while valvular pulmonary stenosis (PS) followed by ventricular septal defect (VSD) were the most common lesions diagnosed in the CHD group (Table 2). Based on echocardiogram and Doppler, rheumatic defects were mild in nine (33%) of the children, moderate in four (15%) and severe in 14 (52%); congenital lesions were mild in 12 (57%), moderate in seven (33%) and severe in two (10%) of the children.

Nineteen (39.6%) of the 48 cardiac children were not diagnosed before the present survey. Of these, seven were among the first group [MR (3), MS (2), DM (2)] and 12 belonged to the second group [PS (4), VSD (3), ASD (3), MVP (1) and PDA (1)]. In the RHD group, a history of rheumatic fever was elicited in only 10 (37%) children, two of whom had two recurrent attacks. None of the children were subjected to throat swab during attacks of sore throat or RF. Four (14.8%) of the children with RHD were taking a regular monthly injection of long-acting penicillin, two (7.4%) were taking the drug irregularly and 21 (77.8%) were not receiving any prophylaxis. None of the CHD children were given prophylaxis against bacterial endocarditis when it was indicated.

Table 1. Number of patients examined and prevalence /1000 of rheumatic heart disease (RHD, group 1) and congenital heart disease (CHD, group 2) according to age and sex.

P values for both age and sex were >0.05; RHD=rheumatic heart disease; CHD=congenital heart disease.

Table 2. Types and percent of cardiac lesion in the study groups.

DM=double mitral; MR=mitral regurgitation; MS=mitral stenosis; AoR=aortic regurgitation; DAo=double aorta;
DT=double tricuspid; PR=pulmonary regurgitation; PS=pulmonary stenosis; VSD=ventricular septal defect; ASD=atrial septal defect; AoS=aortic stenosis; MVP=mitral valve prolapse; PDA=patent ductus arteriosus.

Table 3. Maternal risk factors.

*=p=0.05 (groups 1 and 2 versus controls); **=p=0.05 (group 2 versus group 1 and controls);  RHD=rheumatic heart disease; CHD=congenital heart disease.

Regarding family history, consanguinity was higher but not statistically significant in only the CHD group compared to the control group, while birth order of the affected child did not differ much between the three groups (data not shown). In seven (33.3%) families of the children with CHD, there were one or more siblings affected with CHD and the difference, compared to the controls, was statistically significant (P<0.001), 6 (22.2%) and 17 (8.5%) children in the RHD and control groups respectively have one or more other siblings affected with RHD (P>0.05).

Table 3 presents results of comparison of the maternal risk factors among the three groups. High multiparity (more than five pregnancies) was statistically higher in Groups 1 and 2 than in the controls (P<0.05). History of previous stillbirth and repeated (more than twice) abortion was reported more frequently by mothers of the CHD children than in the other two groups (P<0.05). Likewise, 23.8% of mothers of the CHD children gave a history of taking contraceptive pills during early pregnancy (by mistake) compared to 7.4% and 6% in mothers of RHD and control children respectively (P<0.05).

In terms of socioeconomic conditions, for each social variable a score was calculated and compared between the two study groups and then to the control group, and the results are summarized in Tables 4 and 5. Parents' age and maternal education and occupation did not differ in the three groups, while the proportion of less educated and unskilled fathers was higher in the RHD and CHD groups than in the controls. The scores of smoking habits of the fathers in the two patient groups were statistically higher than in the controls. In the RHD group, the score of family income was much less than in the control group; the CHD group did not show the same result.

As shown in Table 5, no major differences were observed with respect to housing conditions except crowding index, water supply, and sewage and refuse disposal among the three groups. Conversely, score of roads, residential units, and combined environmental conditions were lower, and crude crowding index was higher in Groups 1 and 2 than in the controls (P<0.05). However, there were no significant differences in these variables between the RHD and CHD groups, though the scores were slightly less in the RHD group.

Discussion

The prevalence of RHD in schoolchildren varies considerably throughout the world.³ It has been reported as 0.6/1000 in the USA¹² and 0.7/1000 in Japan,¹³ while in developing countries, prevalence rates ranging from 0.3/1000 to 18.6/1000 have been reported.³ Our rate (3.4/1000) is high compared to rates found in industrialized countries, and is also higher than figures reported from some areas in the developing world, as in Cote d'Ivoire (1.9/1000), Nigeria (0.3/1000), Uruguay (1.0/1000) and China (0.4/1000).³ It appears also that schoolchildren in Menoufia have a higher rate than those found earlier in other areas of Egypt where prevalence rates of 1.3/1000 in the Western Desert Coast⁸ and 0.7/1000 in Alexandria¹⁰ were reported. Further, children with severe RHD are likely to drop out of school and this may have underestimated the true prevalence of RHD in the present survey. However, there were no medical records for those children in the schools visited.

Table 4. Mean standard deviation (SD) of scores of social variables in patients and controls.

*=result of p value; a & b significant & insignificant between the 3 groups, respectively; c & d significant & insignificant between RHD group & control, respectively; e & f significant & insignificant between CHD group & control, respectively; j & h significant & insignificant between RHD & CHD groups, respectively; RHD=rheumatic heart disease; CHD=congenital heart disease.

Table 5. Mean standard deviation (SD) of environmental factors and crowding index in patients and controls.

 *=result of p value; a & b significant & insignificant between the 3 groups, respectively; c & d significant & insignificant between RHD group & control, respectively; e & f significant & insignificant between CHD group & control, respectively; j & h significant & insignificant between RHD & CHD groups, respectively; RHD=rheumatic heart disease; CHD=congenital heart disease.

The high prevalence of RHD in Menoufia schoolchildren could largely be attributed to the low standard of living found in their families. Our children with RHD have the lowest scores of social environment and the highest crude crowding index compared to the other groups (Tables 4 and 5). The decline in the prevalence of RHD in industrialized countries has largely been attributed to the improvement in the standard of living,¹⁴ and the persistence of this major public health problem in developing countries is mainly due to of low social circumstances and poverty.^3,15 The low scores of education, income and occupation of the head of the family in the RHD group have previously been observed in studies of RHD prevalence.^16-18 Poverty and illiteracy breed overcrowding, which promotes the spread of many infections which, due to ignorance and scarcity of health facilities, are often neglected until complications set in, as in RF.^15,17,18

Previous studies of the incidence of affected valves in RHD have reported the mitral valve as the most common valve affected^4,19 and this is consistent with our findings (Table 2). Unfortunately, combined MR and MS found in the majority of our children are said to favor the onset of bacterial endocarditis.²⁰ Furthermore, severe and multiple valvular damage as observed in our children indicates previous severe attack of rheumatic carditis and is more common in children of developing countries than those of developed countries.¹⁶

Failure to initiate and/or comply with penicillin prophylaxis was found in more than half of our RHD children and similar findings have previously been reported in Egypt¹⁸ and in other countries.^4,19Factors contributing to failure of penicillin prophylaxis include: children not subjected to throat culture during throat infection, seven patients not diagnosed before the study, fear of penicillin, illiteracy of some parents, and inadequate medical supervision. It has been shown that the natural history of RF can be dramatically altered by effective penicillin prophylaxis at different points of the disease.^3,20-22

There is little information on the prevalence of CHD in schoolchildren in Egypt. The prevalence found in this study (2.4/1000) is not markedly different from rates reported from other areas of the world.^23-25

A hereditary predisposition for cardiac anomalies together with an environmental trigger during early pregnancy is currently the most accepted explanation for the cause of CHD.^6,7 In the present study, the high percentage of consanguineous marriage, other siblings affected, stillbirth and abortion in families of the CHD children may reflect a hereditary predisposition for the cardiac defects. On the other hand, high multiparity, drug abuse during pregnancy, maternal trauma, father smoking and low score of the whole social environment found in the CHD families (Tables 3 and 4) may be contributing environmental factors to the occurrence of CHD. However, these findings should be interpreted with caution since maternal history of exposure to environmental risk factors during previous pregnancy may be biased by maternal memory. Another study is needed in the same area and at the time of birth to evaluate the relationship between environmental factors and the occurrence of CHD. Several previous studies have observed that both hereditary and environmental risk factors are associated with CHD.^2,6,7,26,27

The finding of PS and not VSD as the most common congenital cardiac lesion and the deficiency of cyanotic defects in our children may be accounted for by the following: 1) many small VSDs close spontaneously before reaching school age; 2) PS was of mild degree and this favors good prognosis; 3) cyanotic lesions may not be seen in our age group or may result in school dropout; and 4) the incidence of individual CHD lesions may be influenced by racial genetic factors.²⁸

A significant number of our children were not diagnosed prior to this study. Mild symptoms of some defects, inadequate medical supervision and unavailability of echocardiogram may explain this finding. However, unless community-based surveys are undertaken, many children with heart disease go undetected.³ Early detection and treatment produce better long-term results for these children and there should be increased attention to cardiovascular examination in routine checkup of schoolchildren. In addition, late diagnosis and lack of a previous history of RF in the majority of our RHD children emphasize the importance of primary penicillin prophylaxis in children with streptococcal sore throat.³

In conclusion, the prevalence of heart disease in schoolchildren of Menoufia is high. This may be related to low socioeconomic level and other environmental risk factors, particularly where RHD is concerned. Improving the standard of living of the community and especially overcrowding in Menoufia is essential for long-term prevention of this problem. However, practical programs at the community and health service levels are needed in the immediate future. At the community level, these programs should focus on education of the general population on the importance of prophylaxis against rheumatic fever and on the importance of antenatal care and avoiding risk factors associated with the occurrence of heart disease. At the level of health services, rheumatic fever prevention programs should be implemented in Menoufia, guided by reliable and recent community-based data. In addition, promotion of the availability of cardiac ultrasound and trained personnel in the local hospitals is needed for the early diagnosis and treatment of heart disease in schoolchildren and the creation of medical records for follow-up of the cases detected.

References