Seven years after hospitalisation for acute lower
respiratory tract infection in infancy, 200 children and
their case -controls were assessed for respiratory status
and epidemiological characteristics. The index group
comprised 100 cases where respiratory syncytial virus had
been responsible for the index illness (RSV +) and 100 cases
in whom this organism had not been found (RSV -).
No differences were noted between index and control
children with respect to birth weight and gestational age,
although breast feeding was more frequently observed in
control children. Index children reported more respiratory
symptoms and asthma as well as other indices of respiratory
illhealth. Although index children appeared to be a socially disadvantaged group, parental respiratory symptoms
and smoking habits were comparable in both groups of
children. The atopic background was similar in index and
control populations. At follow -up, index children were
shorter than controls, although their weights were comparable.
Tests of respiratory function were diminished in index children,
who also had evidence of bronchial hyperreactivity.
RSV+ and RSV- index children showed similar clinical
characteristics and atopic background. No significant
differences were found in the age at which the index illness occurred, or in the proportion who were breast -fed. The
results of tests of respiratory function and exercise
test were comparable in RSV+ and RSV- children.
Children who had suffered bronchitis, bronchiolitis
or pneumonia had similar clinical characteristics compared
to their controls, with the exception that fewer children
who had bronchiolitis were breast -fed, and children who
suffered pneumonia were of lower birth weight. All three
sub -groups of index children reported more respiratory
symptoms and ill health than their controls. Social and
family factors were less favourable when compared to control
children. The atopic background was similar between the
three disease categories, and also between index and control
children. Tests of respiratory function were significantly
reduced only in children who had bronchiolitis, although
the trend in the bronchitis and pneumonia children was also
towards poorer function. A one -way analysis of variance
between disease categories on the differences between case
and control for each respiratory function measurement
showed that differences within a disease category was geater
than the differences between disease categories.
Following the index illness, children were reported
to cough, wheeze or remain asymptomatic. Those with symptoms
were almost identical in terms of clinical, social and family
characteristics, as well as atopic background; but differed from their controls. Tests of respiratory function were
diminished in both groups of symptomatic children, with
evidence of bronchial hyper- reactivity. The asymptomatic
index children did not differ from the symptomatic children
with respect to social factors, suggesting that these
contribute little to the occurrence of respiratory symptoms.
Asymptomatic children were of similar height to their
controls. Respiratory function was also comparable although
there was a slight trend to hyper- reactive airways.
Children whose index illness was attributed solely to
acute infections (RSV +, non -atopic) reported similar
occurrences of respiratory symptoms to their controls.
Respiratory function was also comparable. When there was
a background history of atopy, children reported more
respiratory symptoms and had significantly lower tests of
respiratory function as well as evidence of bronchial
hyperreactivity when compared with controls. The results
suggest that atopy is a determinant of poor respiratory
function, but they may have also been influenced by the
discrepancy in numbers. Bronchial reactivity was present
in excess in atopic and non -atopic index cases, despite
being significant only in the atopic children.
Index children with bronchial reactivity showed
similar clinical, atopic, social and family characteristics
to those without evidence of hyperreactive airways, but these two groups differed clinically and in social and family
background from control children. Those with bronchial
reactivity wheezed more, and there was a greater percentage
of asthmatics. Respiratory function was significantly
diminished compared to controls. There was no excess of
atopic disorders in the index children with hyperreactive
airways.
Children without evidence of hyperreactive airways
also reported more respiratory symptoms, but bronchitis
rather than asthma was diagnosed in these children. Except
for a lower PEFR, all other tests of respiratory function
were similar between index and control children.
Ventilatory dysfunction paralleled bronchial reactivity.
It is not clear which is of primary importance, or if there
is any relationship between the two. Acute respiratory
infection may have caused both these abnormalities, or they
could have predated the event, rendering children more
susceptible to infection.
