768
BRITISH MEDICAL JOURNAL
further illustrated by the discrepancy between these two pairs of authors in their estimates of the prevalence of regular cornflake-eating, those of Drs Rawcliffe and Truelove being substantially and significantly higher. I agree with Drs Archer and Harvey that none of us has yet answered this potentially important question. In the light of experience so far I suggest that any future case-control study of a possible dietary factor in Crohn's disease should observe three principles. Firstly, it should record pre-illness habits. Secondly, the cases should be freshly diagnosed and should have had symptoms for less than a year or so. And, thirdly, the information should be secured by a questionnaire which can be administered without interview: this should both make it possible to collect data from more than one centre and do much to eliminate bias in either direction. A H JAMEs
9 SEPTEMBER 1978
week before the development of the disease. Among the 74 controls 29 (39%) ate cornflakes with similar frequency. There were 21 Crohn's patients still eating cornflakes, of whom 10 had had recurrence. Forty-seven of the patients had either never eaten cornflakes, or did so only rarely; 18 of these had had recurrence (X2 = 0o52; P > 0*5). The anatomical distribution of Crohn's disease was the same in both groups. The Crohn's patients consumed on average 10 teaspoonfuls of sugar per day and the controls seven (P=0.0009). This would confirm Martini and Brandes's observation that patients with Crohn's disease consume more sugar than those without.' In this series of patients it would appear that the eating of cornflakes was not associated with the development of Crohn's disease and that it did not affect the recurrence rate of Crohn's disease, or the intestinal distribution. However, there does appear to be a significant association between increased sugar conHillingdon Hospital, sumption and Crohn's disease. Our findings Uxbridge. Middx are thus in agreement with those of Drs Martini, G A, and Brandes, J W, Klinische Wochen- Rawciffe and Truelove and of Drs Archer and schrift, 1976, 54, 367. 'Miller, B, et al, Verhandlungen der deutschen Gesell. Harvey but would disagree with those of Dr schaft fur innere Medizin, 1976, 82, 922. A H James (9 April 1977, p 943). 3Gardner, M J, and James, A H, British Medical Journal, 1977, 2, 826. W B GRAHAM BRUCE TORRANCE SIR,-We would like to add a note to the con- Manchester Royal Infirmary, flicting results reported on the consumption Manchester of comflakes (9 April 1977, p 943; 19 August, T V TAYLOR pp 539 and 540) and the development of Royal Infirmary, Crohn's disease. In a study shortly to be published in Edinburgh Clinical and Experimental Immunology we have Martini, G A, and Brandes, J W, Klinische Wochenschrift, 1976, 54, 367. investigated the incidence of antibodies to maize in Crohn's disease and other intestinal disorders, using an indirect immunofluorescent technique. Although 33 % of the patients with Whooping cough
in that outbreak on such a scale as to be susceptible to a 46%' attack rate now ? In the studies in Glasgow to which he refers1 2 we found that children born in the epidemic years 1967-8 and 1970-1 had lower attack rates in the 1970-1 and 1-974-5 epidemics irrespective of vaccination. It is difficult to see how this could be otherwise unless a large proportion of young children have second attacks of whooping cough or unless there are substantial errors in diagnosis somewhere along the line. This raises further questions about the distribution of the 23 bacteriologically positive and 34 bacteriologically negative patients in Dr Jenkinson's study; about the 79% attack rate in sibs who cannot all have been unprotected infants because in them the overall attack rate was so much lower; and also about the distribution by age and living conditions of the severe cases which he describes. In Glasgow we are less fortunate than Dr Jenkinson in that the majority of children are in social classes IV and V, not II and III. Even so, the outbreak here is patchy and mild. There are no deaths so far, in fact no deaths since 1970 despite three outbreaks. Like Dr Jenkinson, we also have fewer notified cases of vaccinated than of unvaccinated children (and a significantly lesser likelihood of notification among vaccinated cases), but we also have an appreciable incidence of bacteriologically positive cases in fully vaccinated children as well as of bacteriologically negative cases in children admitted to hospital and notified as whooping cough. GORDON T STEWART
SIR,-At first glance Dr Douglas Jenkinson's article (19 August, p 577) suggests that vaccination with DPT confers substantial protection against whooping cough, especially in children born in 1976. If the high attack rates in his outbreak are compared with the complete rates of vaccination, however, as in the table below, some questions arise. It will be seen that attack rates and relative risk of contracting infection in vaccinated children decrease with age; but so also does the overall attack rate and the attack rate in the unvaccinated children in successive birth cohorts since 1974 to the extent that the lowest attack rate (10-3%) is in the 1977 cohort which is unvaccinated or incompletely vaccinated. The highest attack rate is in children bom in 1974, who presumably were exposed to infection in the 1974-5 outbreak when, according to Dr Jenkinson, over 50% were vaccinated and therefore, on his current estimates for children of that age, completely protected. How did the 76 children (45%) who were unprotected then escape infection
1 Bassili, W R, and Stewart, G T, Lancet, 1976, 1, 471. 2Stewart, G T, Lancet, 1977, 1, 234.
Crohn's disease had antibodies compared with 14 % of the controls, antibodies were present in an even greater proportion of patients with coeliac disease and ulcerative colitis. We conclude that humoral immunity to maize is not of significance in the pathogenesis of Crohn's disease. P J WHORWELL
I W DAVIDSON
Professorial Medical Unit, Southampton General Hospital, Southampton
SIR,-In addition to the recent reports of Drs P M Rawcliffe and S C Truelove (19 August, p 539) and Drs L N J Archer and R F Harvey (p 540) regarding breakfast habits and Crohn's disease we would like to describe our own findings in a group of patients from the Manchester area with Crohn's disease. A total of 68 patients with Crohn's disease under the care of one of us (BT), in 67 of whom the diagnosis was proved histologically at operation, were surveyed by questionnaire about their breakfast habits before and after developing the disease. They were compared with 74 age- and sex-matched controls who had no gastrointestinal disorder. The patients Attack rates were studied with regard to their eating of breakfast cereals and cooked foods, the incidence of recurrence of Crohn's disease among those still eating cereals, particularly cornchildren flakes, and the site of Crohn's disease in rela- All . Vaccinated children tion to the eating of cornflakes. The con- Unvaccinated . children Relative risk (vaccinated/unvaccinated) sumption of sugar was also studied. Of the 68 patients with Crohn's disease, 26 Vaccination% (38-1 %) had eaten cornflakes at least once a
University Department of Community Medicine, Ruchill Hospital, Glasgow
SIR,-It would appear from the figures compiled by Dr Douglas Jenkinson (12 August, p 577) and those reported by Dr G Dick (p 562) that whooping cough is a much less serious disease than it used to be, while on the other hand it is also clear that vaccination is more efficacious and less likely to cause side effects than appeared to be the case a decade ago. Our experience in a busy children's hospital would suggest that the lower mortality remarked on by Dr Dick has not been due to a lower incidence or decreased severity of the disease in the vulnerable set of children under 1 year of age but to earlier recognition and better management now that most children's units are prepared and equipped to nurse such cases.
This leaves unanswered the question of whether universal vaccination would be likely to lower the incidence in babies too young
1973 .
.18-6 .8-6 486 0-18 75
1974
Birth cohorts 1975
1976
1977
18-1
17-0
10-3
10-3
25-1 7-7 46-1 0-17
2-6 37-1 007
24-5
54
55
30
00 00
-
BRITISH MEDICAL JOURNAL
further illustrated by the discrepancy between these two pairs of authors in their estimates of the prevalence of regular cornflake-eating, those of Drs Rawcliffe and Truelove being substantially and significantly higher. I agree with Drs Archer and Harvey that none of us has yet answered this potentially important question. In the light of experience so far I suggest that any future case-control study of a possible dietary factor in Crohn's disease should observe three principles. Firstly, it should record pre-illness habits. Secondly, the cases should be freshly diagnosed and should have had symptoms for less than a year or so. And, thirdly, the information should be secured by a questionnaire which can be administered without interview: this should both make it possible to collect data from more than one centre and do much to eliminate bias in either direction. A H JAMEs
9 SEPTEMBER 1978
week before the development of the disease. Among the 74 controls 29 (39%) ate cornflakes with similar frequency. There were 21 Crohn's patients still eating cornflakes, of whom 10 had had recurrence. Forty-seven of the patients had either never eaten cornflakes, or did so only rarely; 18 of these had had recurrence (X2 = 0o52; P > 0*5). The anatomical distribution of Crohn's disease was the same in both groups. The Crohn's patients consumed on average 10 teaspoonfuls of sugar per day and the controls seven (P=0.0009). This would confirm Martini and Brandes's observation that patients with Crohn's disease consume more sugar than those without.' In this series of patients it would appear that the eating of cornflakes was not associated with the development of Crohn's disease and that it did not affect the recurrence rate of Crohn's disease, or the intestinal distribution. However, there does appear to be a significant association between increased sugar conHillingdon Hospital, sumption and Crohn's disease. Our findings Uxbridge. Middx are thus in agreement with those of Drs Martini, G A, and Brandes, J W, Klinische Wochen- Rawciffe and Truelove and of Drs Archer and schrift, 1976, 54, 367. 'Miller, B, et al, Verhandlungen der deutschen Gesell. Harvey but would disagree with those of Dr schaft fur innere Medizin, 1976, 82, 922. A H James (9 April 1977, p 943). 3Gardner, M J, and James, A H, British Medical Journal, 1977, 2, 826. W B GRAHAM BRUCE TORRANCE SIR,-We would like to add a note to the con- Manchester Royal Infirmary, flicting results reported on the consumption Manchester of comflakes (9 April 1977, p 943; 19 August, T V TAYLOR pp 539 and 540) and the development of Royal Infirmary, Crohn's disease. In a study shortly to be published in Edinburgh Clinical and Experimental Immunology we have Martini, G A, and Brandes, J W, Klinische Wochenschrift, 1976, 54, 367. investigated the incidence of antibodies to maize in Crohn's disease and other intestinal disorders, using an indirect immunofluorescent technique. Although 33 % of the patients with Whooping cough
in that outbreak on such a scale as to be susceptible to a 46%' attack rate now ? In the studies in Glasgow to which he refers1 2 we found that children born in the epidemic years 1967-8 and 1970-1 had lower attack rates in the 1970-1 and 1-974-5 epidemics irrespective of vaccination. It is difficult to see how this could be otherwise unless a large proportion of young children have second attacks of whooping cough or unless there are substantial errors in diagnosis somewhere along the line. This raises further questions about the distribution of the 23 bacteriologically positive and 34 bacteriologically negative patients in Dr Jenkinson's study; about the 79% attack rate in sibs who cannot all have been unprotected infants because in them the overall attack rate was so much lower; and also about the distribution by age and living conditions of the severe cases which he describes. In Glasgow we are less fortunate than Dr Jenkinson in that the majority of children are in social classes IV and V, not II and III. Even so, the outbreak here is patchy and mild. There are no deaths so far, in fact no deaths since 1970 despite three outbreaks. Like Dr Jenkinson, we also have fewer notified cases of vaccinated than of unvaccinated children (and a significantly lesser likelihood of notification among vaccinated cases), but we also have an appreciable incidence of bacteriologically positive cases in fully vaccinated children as well as of bacteriologically negative cases in children admitted to hospital and notified as whooping cough. GORDON T STEWART
SIR,-At first glance Dr Douglas Jenkinson's article (19 August, p 577) suggests that vaccination with DPT confers substantial protection against whooping cough, especially in children born in 1976. If the high attack rates in his outbreak are compared with the complete rates of vaccination, however, as in the table below, some questions arise. It will be seen that attack rates and relative risk of contracting infection in vaccinated children decrease with age; but so also does the overall attack rate and the attack rate in the unvaccinated children in successive birth cohorts since 1974 to the extent that the lowest attack rate (10-3%) is in the 1977 cohort which is unvaccinated or incompletely vaccinated. The highest attack rate is in children bom in 1974, who presumably were exposed to infection in the 1974-5 outbreak when, according to Dr Jenkinson, over 50% were vaccinated and therefore, on his current estimates for children of that age, completely protected. How did the 76 children (45%) who were unprotected then escape infection
1 Bassili, W R, and Stewart, G T, Lancet, 1976, 1, 471. 2Stewart, G T, Lancet, 1977, 1, 234.
Crohn's disease had antibodies compared with 14 % of the controls, antibodies were present in an even greater proportion of patients with coeliac disease and ulcerative colitis. We conclude that humoral immunity to maize is not of significance in the pathogenesis of Crohn's disease. P J WHORWELL
I W DAVIDSON
Professorial Medical Unit, Southampton General Hospital, Southampton
SIR,-In addition to the recent reports of Drs P M Rawcliffe and S C Truelove (19 August, p 539) and Drs L N J Archer and R F Harvey (p 540) regarding breakfast habits and Crohn's disease we would like to describe our own findings in a group of patients from the Manchester area with Crohn's disease. A total of 68 patients with Crohn's disease under the care of one of us (BT), in 67 of whom the diagnosis was proved histologically at operation, were surveyed by questionnaire about their breakfast habits before and after developing the disease. They were compared with 74 age- and sex-matched controls who had no gastrointestinal disorder. The patients Attack rates were studied with regard to their eating of breakfast cereals and cooked foods, the incidence of recurrence of Crohn's disease among those still eating cereals, particularly cornchildren flakes, and the site of Crohn's disease in rela- All . Vaccinated children tion to the eating of cornflakes. The con- Unvaccinated . children Relative risk (vaccinated/unvaccinated) sumption of sugar was also studied. Of the 68 patients with Crohn's disease, 26 Vaccination% (38-1 %) had eaten cornflakes at least once a
University Department of Community Medicine, Ruchill Hospital, Glasgow
SIR,-It would appear from the figures compiled by Dr Douglas Jenkinson (12 August, p 577) and those reported by Dr G Dick (p 562) that whooping cough is a much less serious disease than it used to be, while on the other hand it is also clear that vaccination is more efficacious and less likely to cause side effects than appeared to be the case a decade ago. Our experience in a busy children's hospital would suggest that the lower mortality remarked on by Dr Dick has not been due to a lower incidence or decreased severity of the disease in the vulnerable set of children under 1 year of age but to earlier recognition and better management now that most children's units are prepared and equipped to nurse such cases.
This leaves unanswered the question of whether universal vaccination would be likely to lower the incidence in babies too young
1973 .
.18-6 .8-6 486 0-18 75
1974
Birth cohorts 1975
1976
1977
18-1
17-0
10-3
10-3
25-1 7-7 46-1 0-17
2-6 37-1 007
24-5
54
55
30
00 00
-
