3
Journal o f Epidemiology a n d Community Health, 1986, 4 1 , 316-318 A case-control study o f acute appendicitis a nd diet i n children M NELSON J MORRIS D J P AN D S SIMMONDS From t h e M RC Environmental Epidemiology Unit, University o f Southampton, Southampton General Hospital, Southampton S 0 9 4 X Y SUMMARY T h e diets o f 5 3 Southampton children w h o h a d h a d appendicitis were compared with those o f t wo sets o f age-sex matched controls using a seven-day weighed food record. O n e s e t o f controls comprised classmates o f t h e cases; t h e other was a random sample o f a l l schoolchildren i n t h e city. T h e cases weighed less and were shorter i n height; they h a d lower intakes o f energy, a l l the main nutrients a nd water. T he differences i n weight a d water intake were statistically significant. L o w water intake was identified a s a risk factor independent o f other factors. Consumption o f dietary fibre from cereals a n d vegetables i n relation t o total energy intake an d body weight was similar i n cases and controls. T h e aetiology o f acute appendicitis remains unknown. T h e evidence i n support o f dietary causes, i n particular lack o f cereal fibre, 2comes largely from international comparisons a n d i s inconclusive.3 Case-control studies o f diet have given inconsistent results.4-8 I n only t wo studies, however, w a s diet measured by a more precise method than a single interview. Both these studies were based o n small numbers o f cases a n d h a d limited statistical power. W e describe a case- control comparison o f 5 3 cases a n d 9 7 controls in which diet w a s assessed b y a 7-day weighed food diary. Method T h e study was an extension o f a n earlier one.4 Th e cases selected were a consecutive series o f 5 5 schoolchildren aged 1 3 to 1 5 years w h o h a d undergone emergency appendicectomy during 1981-4 a n d were resident i n Southampton. Acute appendicitis h a d been confirmed by macroscopic a n d histological examination. Each case w a s seen between o n e a n d 1 2 months after t h e operation. F o r each case t w o controls w h o ha d n o t h a d appendicitis were selected. T h e first w a s drawn randomly from t h e class register o f t h e case; t h e second w a s a child randomly selected from t h e Southampton school registers. T h e controls were matched f o r s e x a n d year of a g e a nd were seen within o n e month o f t h e case. With help from their parents, each case a n d control weighed a n d recorded food a n d drink consumed during o n e week. T h e height a n d weight o f each child were measured. F o r t w o cases neither control completed t he weighed food record a n d they were therefore excluded. I n t h e analysis t h e results f o r t h e initial 3 0 cases, previously reported, were combined with those f o r t h e subsequent 2 3 . With this number o f cases recording diet over seven days, a n d with estimated between- a n d within-person variances i n intake derived from t h e Cambridge Family Food Survey,9 this combined study h a d a n estimated chance o f detecting a difference ( at t h e 5 significance level o f 3 0g in average daily fibre intake between t h e cases a n d both control groups combined. T w o w a y analysis o f variance wa s used t o test f o r differences i n body size a n d nutrient intake between cases n d their matched controls a n d between t h e t w o control groups. Results T h e cases comprised 3 4 boys a n d 1 9 girls. Fifty o n e o f their 5 5 classmates  first controls) a n d 46 of t h e 5 5 randomly selected schoolchildren (second controls) completed t h e weighed food diaries. T h e social class distribution o f cases a n d controls w a s similar. There were n o statistically significant differences i n body size or nutrient intake between t h e t w o control groups. T he results f o r t h e controls a r e therefore given f o r t h e two groups combined. T h e average weight o f t h e cases, 5 1 lkg, w a s less than that o f t h e controls, 54-9kg (table 1 . T h e cases were also shorter, their mean height being 1-61m compared with 1 *64m. These differences between cases a n d controls were statistically significant f o r weight 3 1 6

A case-control study of acute appendicitis and diet in children

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Page 1: A case-control study of acute appendicitis and diet in children

 

J o u r n a l

o f E p i d e m i o l o g y

a n d

C o m m u n i t y

H e a l t h , 1 9 8 6 ,

4 1 , 3 1 6 - 3 1 8

A c a s e - c o n t r o l

s t u d y

o f

a c u t e

a p p e n d i c i t i s

a n d

d i e t

i n

c h i l d r e n

M NELSON

J

MORRIS

DJP

AND

S SIMMONDS

F r o m t h e

MRC

E n v i r o n m e n t a l

E p i d e m i o l o g y

U n i t ,

U n i v e r s i t y

o f

S o u t h a m p t o n ,

S o u t h a m p t o n

G e n e r a l

H o s p i t a l ,

S o u t h a m p t o n

S09

4XY

SUMMARY

T h e d i e t s

o f 5 3 S o u t h a m p t o n

c h i l d r e n

who

h a d h a d a p p e n d i c i t i s

were c o m p a r e d

w i t h

t h o s e o f

two s e t s o f

age-sex

m a t c h e d

c o n t r o l s

u s i n g a s e v e n - d a y

w e i g h e d

f o o d r e c o r d .

One s e t

o f

c o n t r o l s

c o m p r i s e d

c l a s s m a t e s

o f t h e c a s e s ;

t h e

o t h e r was

a r a n d o m

s a m p l e

o f

a l l s c h o o l c h i l d r e n

i n

t h e

c i t y .

T h e

cases w e i g h e d

l e s s

a n d were

s h o r t e r

i n h e i g h t ;

t h e y

h a d l o w e r

i n t a k e s

o f energy,

a l l

t h e

m a i n

n u t r i e n t s

a n d

w a t e r .

T h e

d i f f e r e n c e s

i n w e i g h t

a d w a t e r

i n t a k e

w er e

s t a t i s t i c a l l y

s i g n i f i c a n t .

Lo w

w a t e r

i n t a k e was i d e n t i f i e d

as

a r i s k f a c t o r i n d e p e n d e n t

o f o t h e r

f a c t o r s .

C o n s u m p t i o n

o f d i e t a r y

f i b r e

f r o m c e r e a l s

a n d

v e g e t a b l e s

i n r e l a t i o n

t o

t o t a l

energy i n t a k e

a n d b o d y

w e i g h t

was s i m i l a r

i n cases

a n d

c o n t r o l s .

T h e

a e t i o l o g y

o f

a c u t e

a p p e n d i c i t i s

r e m a i n s

u n k n o w n .

T h e e v i d e n c e

i n s u p p o r t

o f d i e t a r y

c a u s e s ,

i n p a r t i c u l a r

l a c k o f c e r e a l f i b r e ,

2 c o m e s l a r g e l y

f r o m i n t e r n a t i o n a l

c o m p a r i s o n s

a n d

i s

i n c o n c l u s i v e . 3

C a s e - c o n t r o l

s t u d i e s

o f d i e t h a v e g i v e n

i n c o n s i s t e n t

r e s u l t s . 4 - 8

I n

o n l y

t w o s t u d i e s , h o w e v e r ,

w a s

d i e t

m e a s u r e d

b y a

m o r e p r e c i s e

m e t h o d

t h a n a s i n g l e

i n t e r v i e w .

B o t h

t h e s e

s t u d i e s

w e r e

b a s e d

o n s m a l l

n u m b e r s

o f

c a s e s a n d

h a d l i m i t e d

s t a t i s t i c a l

p o w e r . We d e s c r i b e

a

c a s e -

c o n t r o l

c o m p a r i s o n

o f 5 3 c a s e s

a n d 9 7 c o n t r o l s

i n

w h i c h

d i e t w a s a s s e s s e d

b y a 7 - d a y

w e i g h e d

f o o d

d i a r y .

M e t h o d

T h e s t u d y

w a s a n e x t e n s i o n

o f a n

e a r l i e r o n e . 4 T h e

c a s e s

s e l e c t e d w e r e

a

c o n s e c u t i v e

s e r i e s o f

5 5

s c h o o l c h i l d r e n

a g e d

1 3 t o 1 5

y e a r s

who h a d

u n d e r g o n e

e m e r g e n c y

a p p e n d i c e c t o m y

d u r i n g

1 9 8 1 - 4

a n d

w e r e

r e s i d e n t

i n

S o u t h a m p t o n .

A c u t e

a p p e n d i c i t i s

h a d b e e n

c o n f i r m e d

b y

m a c r o s c o p i c

a n d h i s t o l o g i c a l

e x a m i n a t i o n .

E a c h c a s e w a s

s e e n b e t w e e n

o n e

a n d

1 2

m o n t h s

a f t e r

t h e

o p e r a t i o n .

F o r

e a c h

c a s e

t w o

c o n t r o l s

who h a d

n o t

h a d

a p p e n d i c i t i s

w e r e

s e l e c t e d .

T h e f i r s t

w a s

d r a w n

r a n d o m l y

f r o m

t h e

c l a s s

r e g i s t e r

o f t h e c a s e ;

t h e

s e c o n d

w a s a c h i l d

r a n d o m l y

s e l e c t e d

f r o m t h e S o u t h a m p t o n

s c h o o l

r e g i s t e r s .

T h e c o n t r o l s

w e r e m a t c h e d

f o r

s e x

a n d

y e a r

o f

a g e

a n d

w e r e

s e e n

w i t h i n o n e

m o n t h o f t h e

c a s e .

W i t h

h e l p

f r o m

t h e i r

p a r e n t s ,

e a c h

c a s e

a n d c o n t r o l

w e i g h e d

a n d r e c o r d e d

f o o d

a n d d r i n k

c o n s u m e d

d u r i n g

o n e

w e e k .

T h e

h e i g h t

a n d

w e i g h t

o f

e a c h

c h i l d

w e r e

m e a s u r e d .

F o r

t w o

c a s e s n e i t h e r

c o n t r o l c o m p l e t e d

t h e

w e i g h e d

f o o d r e c o r d

a n d

t h e y

w e r e

t h e r e f o r e

e x c l u d e d .

I n t h e

a n a l y s i s

t h e

r e s u l t s f o r

t h e i n i t i a l

3 0

c a s e s ,

p r e v i o u s l y

r e p o r t e d ,

w e r e c o m b i n e d

w i t h t h o s e f o r

t h e

s u b s e q u e n t

2 3 .

W i t h t h i s n u m b e r

o f c a s e s r e c o r d i n g

d i e t

o v e r s e v e n d a y s ,

a n d

w i t h e s t i m a t e d

b e t w e e n -

a n d

w i t h i n - p e r s o n

v a r i a n c e s

i n i n t a k e

d e r i v e d

f r o m t h e

C a m b r i d g e

F a m i l y

F o o d

S u r v e y , 9

t h i s c o m b i n e d

s t u d y

h a d a n e s t i m a t e d

c h a n c e

o f

d e t e c t i n g

a

d i f f e r e n c e ( a t

t h e

5

s i g n i f i c a n c e

l e v e l

o f 3

0 g

i n

a v e r a g e d a i l y

f i b r e

i n t a k e

b e t w e e n

t h e

c a s e s

a n d

b o t h

c o n t r o l g r o u p s

c o m b i n e d .

Two w a y

a n a l y s i s

o f v a r i a n c e

w a s u s e d

t o

t e s t

f o r

d i f f e r e n c e s

i n

b o d y

s i z e

a n d

n u t r i e n t

i n t a k e b e t w e e n

c a s e s

n d t h e i r

m a t c h e d

c o n t r o l s

a n d

b e t w e e n

t h e

t w o

c o n t r o l g r o u p s .

R e s u l t s

T h e c a s e s c o m p r i s e d

3 4

b o y s

a n d

1 9

g i r l s .

F i f t y

o n e

o f

t h e i r

5 5

c l a s s m a t e s

  f i r s t

c o n t r o l s )

a n d

4 6 o f t h e

5 5

r a n d o m l y

s e l e c t e d

s c h o o l c h i l d r e n

( s e c o n d

c o n t r o l s )

c o m p l e t e d

t h e

w e i g h e d

f o o d d i a r i e s .

T h e s o c i a l

c l a s s

d i s t r i b u t i o n

o f c a s e s

a n d

c o n t r o l s

was

s i m i l a r .

T h e r e

w e r e

n o

s t a t i s t i c a l l y

s i g n i f i c a n t

d i f f e r e n c e s

i n

b o d y

s i z e

o r

n u t r i e n t

i n t a k e

b e t w e e n

t h e

t w o c o n t r o l

g r o u p s .

T h e

r e s u l t s

f o r

t h e c o n t r o l s

a r e

t h e r e f o r e

g i v e n

f o r

t h e

t w o

g r o u p s

c o m b i n e d .

T h e a v e r a g e

w e i g h t

o f

t h e

c a s e s ,

5 1

l k g ,

was l e s s

t h a n

t h a t o f

t h e

c o n t r o l s ,

5 4 - 9 k g ( t a b l e

1 .

T h e c a s e s

w e r e

a l s o s h o r t e r ,

t h e i r

mean

h e i g h t

b e i n g

1 - 6 1 m

c o m p a r e d

w i t h

1

* 6 4 m .

T h e s e d i f f e r e n c e s

b e t w e e n

c a s e s

a n d c o n t r o l s

w e r e s t a t i s t i c a l l y s i g n i f i c a n t

f o r

w e i g h t

3 1 6

Page 2: A case-control study of acute appendicitis and diet in children

 

A c a s e - c o n t r o l

s t u d y o f

a c u t e a p p e n d i c i t i s

a n d d i e t i n c h i l d r e n

( p

 

0 - 0 3 )

a n d on t h e

b o r d e r l i n e o f

s i g n i f i c a n c e f o r

h e i g h t ( p

 

0 - 0 5 ) .

H o w e v e r ,

t h e d i f f e r e n c e i n

b o d y

mass i n d e x

( w e i g h t / h e i g h t 2 )

w a s

s m a l l a n d

n o t

s i g n i f i c a n t .

I n

c o m p a r i s o n

w i t h

t h e c o n t r o l

groups

t h e cases

h a d

a

l o w e r mean d a i l y

i n t a k e o f

e n e r g y , p r o t e i n ,

f a t ,

c a r b o h y d r a t e ,

a n d

w a t e r

( t a b l e 2 .

C a r b o h y d r a t e

i s

t o t a l

a v a i l a b l e

c a r b o h y d r a t e

f r o m

sugar

a n d

s t a r c h e s .

W a t e r

i n c l u d e s a l l t h e w a t e r c o n t a i n e d

i n

f o o d s

a n d

b e v e r a g e s .

None o f t h e d i f f e r e n c e s was

s t a t i s t i c a l l y

s i g n i f i c a n t

a t

t e 5 l e v e l .

L o g a r i t h m i c

v a l u e s o f

w a t e r

i n t a k e

w ere u s e d i n t h e

a n a l y s i s b e c a u s e

t h e i r

d i s t r i b u t i o n was s k e w e d . T h e d i f f e r e n c e i n

w a t e r

i n t a k e f e l l

j u s t

s h o r t o f

s t a t i s t i c a l

s i g n i f i c a n c e

  p = 0 - 0 6 ) .

T a b l e 3

s h o w s t h e c o n s u m p t i o n

o f

d i e t a r y

f i b r e

d e r i v e d f r o m

v e g e t a b l e

a n d c e r e a l f o o d s .

L o g a r i t h m i c

v a l u e s o f t o t a l v e g e t a b l e a n d

p o t a t o f i b r e

a n d

c e r e a l

f i b r e

c o n s u m p t i o n

f r o m b r e a d were u s e d i n t h e

T a b l e 1

Mean w e i g h t ,

h e i g h t a n d b o d y m a s s

i n d e x o f

a p p e n d i c i t i s cases a n d

age-sex m a t c h e d c o n t r o l s .

C a s e s C o n t r o l s

D i f f e r e n c e

W e i g h t ( k g ) 5 1 - 1

5 4 9

-38

H e i g h t

  m )

1 - 6 1

1 - 6 4

 

0 0 3

 -0

0 5 , 0

0 0 )

BMI

( k g / m r )

1 9 - 6 2 0 - 4

- 0 - 8

( - 1 - 7 , 0 - 0 8 )

F i g u r e s

i n

p a r e n t h e s e a are 95

c o n f i d e n c e i n t e r v a l s .

T a b l e 2

Mean

d a i l y

i n t a k e s o f energy, n u t r i e n t s ,

a n d water i n

a p p e n d i c i t i s

cases a n d age-sex

m a t c h e d c o n t r o l s .

C a s e s

C o n t r o l s

D i f f e r e n c e

E n e r g y   M J ) 8 - 9 9 - 5 - 0 - 6  -12,0 0 3 )

P r o t e i n

( g )

6 5

6 8 -2.9

  7 - 5 , 1 - 7 )

F a t

( g ) 8 9

96

- 6 - 6   - 1 4 - 4 , 1 - 2 )

C a r b o h y d r a t e

( g ) 2 8 1 2 9 8

-1 7   - 3 6 , 2 )

W a t e r

( g )

1 2 8 7

1 3 9 3 -108   - 2 0 9 , 1 )

F i g u r e s i n

p a r e n t h e s e s ar e 95 c o n f i d e n c e i n t e r v a l s .

* l o g v a l u e s u s e d i n a n a l y s i s o f v a r i a n c e a n d

i n c a l c u l a t i o n o f

c o n f i d e n c e i n t e r v a l s

( g e o m e t r i c

m e a n s s h o w n i n

t a b l e ) .

T a b l e 3

Mean i n t a k e s o f d i e t a r y f i b r e

( g l p e r s o n / d a y )

i n

a p p e n d i c i t i s cases a n d a g e - s e x m a t c h e d c o n t r o l s .

S o u r c e

o f f i b r e

C a s e s C o n t r o l s

D i f f e r e n c e

A l l

v e g e t a b l e s 8 - 6 8 - 5

0 1   - 0 - 8 , 1 - 1 )

P o t a t o e s a 4 0 5 4 - 0 0 0 - 0 5

 -0

5 , 0

7 )

O t h e r

t h a n

p o t a t o e s 4 - 6 5 4 - 6 8 -0-03   - 0 9 , 0 8 )

C e r e a l s

7 - 8 9 - 1 -1-3   - 2 - 6 , 0 - 1 )

B r e a d *

2 - 8 3 1 -0-4   - 0 9 , 0 - 3 )

O t h e r

c e r e a l f o o d s

4 - 5 5 1

-0-6 - 1 - 6 , 0 4 )

T o t a l

1 9 0 2 0 - 5

 1 5   -3 0 , 0 0 )

F i g u r e s

i n

p a r e n t h e s e s

ar e 95 c o n f i d e n c e i n t e r v a l s .

l o g

v a l u e s i n

a n a l y s i s

o f

v a r i a n c e a n d

i n c a l c u l a t i o n o f c o n f i d e n c e i n t e r v a l s

( g e o m e t r i c

m e a n s

s h o w n i n

t a b l e ) .

T a b l e 4

R e l a t i v e

r i s k

o f a p p e n d i c i t i s a c c o r d i n g t o t h i r d s

o f t h e

d i s t r i b u t i o n

o f w e i g h t

a n d

w a t e r

i n t a k e

a m o n g

a p p e n d i c i t i s

c o n t r o l s .

T h i r d s

o f

d i s t r i b u t i o n

U p p e r

M i d d l e

L o w e r

W e i g h t

  2 - 1 2 2

( 0 - 8 - 5 1 ( 0 - 9 - 5 - 3 )

W a t e r

i n t a k e   2 - 4 3 - 0

( 0 - 9 - 6 - 1 )

( 1

1 - 8 - 7 )

F i g u r e s

i n

p a r e n t h e s e s

a r e 95 c o n f i d e n c e i n t e r v a l s

s t a t i s t i c a l

a n a l y s i s . T h e r e w a s n o c o n s i s t e n t d i f f e r e n c e

b e t w e e n

c a s e s

a n d c o n t r o l s

i n

v e g e t a b l e f i b r e .

H o w e v e r , u s i n g

t h e m e t h o d o f S o u t h g a t e e t

a l , ° 0

c e r e a l

f i b r e

c o n s u m p t i o n

f r o m b r e a d a n d o t h e r c e r e a l

f o o d s

w a s l o w e r

a m o n g t h e

c a s e s , 7 - 8 g c o m p a r e d

w i th 9

1 g .

T h i s

d i f f e r e n c e w a s

n o t s t a t i s t i c a l l y

s i g n i f i c a n t

( p =

0 0 7 ) . I n d i v i d u a l

t o t a l f i b r e i n t a k e s

r a n g e d

f r o m

8 - 7 g

t o

3 7 T 7 g

i n

t h e c a s e s a n d f r o m

8 - 4 g

t o

3 4 - 3 g

i n

t h e

c o n t r o l s .

Among t h e c a s e s

a n d c o n t r o l s

t h e r e w a s

a

p o s i t i v e

c o r r e l a t i o n b e t w e e n t h e m e a n

d a i l y i n t a k e s o f f i b r e

a n d

e n e r g y ( r = 0 - 6 5 , p<

0 0 1 ) .

When f i b r e i n t a k e

i s

e x p r e s s e d i n

r e l a t i o n

t o

e n e r g y t h e r e w a s n o

s i g n i f i c a n t

d i f f e r e n c e b e t w e e n c a s e s a n d c o n t r o l s

i n e i t h e r

c e r e a l

o r

v e g e t a b l e f i b r e . T h e

mean

t o t a l f i b r e i n t a k e o f

c a s e s

w a s 2 - 1 7 g / l O O O k J c o m p a r e d

w i t h

2 - 1 8 g / l O O O k J

i n

t h e

c o n t r o l s .

T h e v a r i a b l e s

a n a l y s e d i n t a b l e s

  t o 3

w e r e

c o n s i d e r e d

t o g e t h e r

i n a

l o g i s t i c

r e g r e s s i o n

f o r

m a t c h e d c a s e s a n d c o n t r o l s

u s i n g

t h e

o b s e r v e d

v a l u e s .

O n l y w e i g h t a n d w a t e r i n t a k e

made

s i g n i f i c a n t i n d e p e n d e n t

c o n t r i b u t i o n s

t o r e l a t i v e

r i s k

o f

a p p e n d i c i t i s .

G r o u p i n g

t h e

d a t a

i n

t h i r d s ,

t h e

r e l a t i v e r i s k f

a p p e n d i c i t i s among

c h i l d r e n i n

t h e

l o w e r

t h i r d o f

w e i g h t d i s t r i b u t i o n

w a s t w i c e

t h a t

o f

t h o s e i n t h e

u p p e r

t h i r d

( t a b l e 4 ) .

T h e r i s k

i n t h e l o w e r

t h i r d o f w a t e r

i n t a k e d i s t r i b u t i o n w a s t h r e e t i m e s

t h a t

i n t h e

u p p e r

t h i r d .

D i s c u s s i o n

I n t h i s

s t u d y

d i e t w a s

m e a s u r e d b y a s e v e n - d a y

w e i g h e d

f o o d r e c o r d , a m o r e

p r e c i s e m e t h o d

t h a n

t h o s e

u s e d

i n

p r e v i o u s c a s e - c o n t r o l

s t u d i e s o f

a p p e n d i c i t i s . T h e

s u b j e c t s w e r e c h i l d r e n , among

w ho m

t h e

i n c i d e n c e o f a p p e n d i c i t i s i s

h i g h e s t . T h e

o n l y

o t h e r

s t u d y

w h i c h

u s e d a

f o o d r e c o r d r a t h e r t h a n

d i e t a r y

r e c a l l w a s

r e s t r i c t e d t o

a d u l t s

a n d t h e f o o d

p o r t i o n s

w e r e

u n w e i g h e d . 8 E x t e n s i o n o f

o u r i n i t i a l

s t u d y t o

5 3 c a s e s a n d 9 7

c o n t r o l s h a s g i v e n i t s t a t i s t i c a l

p o w e r

t o d e t e c t

s m a l l d i f f e r e n c e s i n d i e t a r y i n t a k e .

T h e m e a n

w e i g h t s a n d h e i g h t s o f t h e c a s e s w e r e l e s s

t h a n

t h o s e o f

b o t h s e t s

o f c o n t r o l s , c l a s s m a t e s , a n d

r a n d o m l y s e l e c t e d

S o u t h a m p t o n s c h o o l c h i l d r e n

3 1 7

Page 3: A case-control study of acute appendicitis and diet in children

 

3 1 8

( t a b l e 1 .

T h e

l o w e r w e i g h t

o f c a s e s c o u l d

r e f l e c t a n

a n o r e c t i c r e s p o n s e t o a p p e n d i c e c t o m y . H o w e v e r ,

w h e n t h e c a s e s w e r e s u b d i v i d e d

a c c o r d i n g t o i n t e r v a l

b e t w e e n o p e r a t i o n a d i n t e r v i e w ,

t h e e n e r g y i n t a k e s

d i d n o t

i n c r e a s e

w i t h

i n c r e a s i n g

i n t e r v a l .

F u r t h e r m o r e ,

t h e s h o r t s t a t u r e

o f c a s e s i n d i c a t e s t h a t

a n o r e c t i c r e s p o n s e c o u l d

n o t

b e t h e s o l e e x p l a n a t i o n

t h e

c a s e - c o n t r o l d i f f e r e n c e s .

A l t h o u g h t h e s o c i a l c l a s s

d i s t r i b u t i o n s o f c a s e s a n d c o n t r o l s a r e s i m i l a r , t h e

s h o r t e r

s t a t u r e o f c a s e s c o u l d n e v e r t h e l e s s r e f l e c t

s o c i o e c o n o m i c d i f f e r e n c e s

w h i c h

i n d e p e n d e n t l y

i n f l u e n c e g r o w t h a n d s u s c e p t i b i l i t y t o a p p e n d i c i t i s .

T h e w a t e r

i n t a k e o f t h e

c a s e s w a s

l e s s t h a n t h a t o f

b o t h s e t s o f c o n t r o l s ( t a b l e

2 ) . M u l t i p l e l o g i s t i c

r e g r e s s i o n s h o w e d t h a t w a t e r

h a d a n e f f e c t t h a t w a s

i n d e p e n d e n t

o f

o t h e r

f a c t o r s , a n d l o w e r i n t a k e w a s

a s s o c i a t e d w i t h a r e l a t i v e r i s k o f 3

0 ( t a b l e 4 ) ,

w i t h

95

c o n f i d e n c e i n t e r v a l ( 1 . 1 - 8 . 7 ) . T h e

m e c h a n i s m

u n d e r l y i n g

t h i s a s s o c i a t i o n

i s u n k n o w n . B o w e l

m o v e m e n t f r e q u e n c y

a n d

t h e r e f o r e , b y

i m p l i c a t i o n ,

b o w e l

t r a n s i t t i m e w e r e n o t r e l a t e d

t o w a t e r i n t a k e i n

t h e c a s e s

a n d

c o n t r o l s .

T h e

mean i n t a k e o f

d i e t a r y

f i b r e w a s l o w e r

i n

t h e

c a s e s ( t a b l e

3 .

T h e d i f f e r e n c e w a s

d e p e n d e n t

o n i n t a k e

o f

c e r e a l r a t h e r

t h a n v e g e t a b l e

f i b r e . H o w e v e r ,

t h e

c a s e s a t e l e s s

o f

a l l

t h e

m a j o r n u t r i e n t s ,

a n d

t h e r e i s

n o

d i f f e r e n c e

b e t w e e n

c a s e s a n d c o n t r o l s

i f f i b r e i n t a k e i s

e x p r e s s e d

i n

r e l a t i o n

t o t o t a l

e n e r g y

c o n s u m p t i o n .

M u l t i p l e l o g i s t i c r e g r e s s i o n

s h o w e d

t h a t

f i b r e

h a d n o

i n d e p e n d e n t

e f f e c t o n a p p e n d i c i t i s .

I n a

r e c e n t

c a s e -

c o n t r o l

s t u d y

i n

W a s h i n g t o n S t a t e , U S A ,

t h e r e w a s n o

s t a t i s t i c a l l y s i g n i f i c a n t

d i f f e r e n c e

i n

t o t a l

f i b r e

i n t a k e

o f

1 3 5 c h i l d r e n w h o h a d

u n d e r g o n e

a p p e n d i c e c t o m y

a n d

2 1 2 c o n t r o l s . 7

T h e r e

w a s , h o w e v e r ,

a

s i g n i f i c a n t

n e g a t i v e

t r e n d i n r e l a t i v e r i s k w i t h

i n c r e a s i n g

i n t a k e o f

c e r t a i n

f i b r e - c o n t a i n i n g

f o o d s , n a m e l y , w h o l e - g r a i n

b r e a d s

a n d c e r e a l s . T h e s e

f i n d i n g s

w e r e b a s e d

o n

t e l e p h o n e

i n t e r v i e w s

w i t h

p a r e n t s , e n q u i r i n g

s o l e l y

a b o u t

f i b r e - c o n t a i n i n g

f o o d s . O u r

s t u d y

s h o w s t h a t

s u c h d a t a c a n n o t

b e

i n t e r p r e t e d

i n

t h e

a b s e n c e

o f

i n f o r m a t i o n

o n o t h e r

n u t r i e n t s , w a t e r ,

a n d

b o d y s i z e ,

a n d t e c o n c l u s i o n t h a t   a

l i b e r a l

i n t a k e o f

w h o l e -

g r a i n

b r e a d s a n d

c e r e a l s

may

d e c r e a s e

t h e r i s k o f

a p p e n d i c i t i s d u r i n g

c h i l d h o o d

i s n o t

j u s t i f i e d .

I n

S w e d e n ,

t h e d i e t s o f 3 1

a d u l t

p a t i e n t s

w i t h

a p p e n d i c i t i s

w e r e

c o m p a r e d

w i t h

t h o s e

o f

3 0

a g e -

m a t c h e d

h o s p i t a l

c o n t r o l s

u s i n g

a

s e v e n - d a y

f o o d

d i a r y . 8

T h e mean f i b r e

i n t a k e

o f c a s e s

w a s

l o w e r

t h a n

t h a t

o f c o n t r o l s a f t e r a l l o w a n c e

f o r

t h e i r

l o w e r

e n e r g y

i n t a k e .

H o w e v e r ,

i

H o n g

K o n g

d i e t

h i s t o r i e s

s h o w e d

n o d i f f e r e n c e

i n

t h e

d i e t a r y

f i b r e i n t a k e

o f

6 7 c a s e s

a n d

c o n t r o l s

  D o n n a n

a n d

H o ,

u n p u b l i s h e d d a t a ) .

Two

s t u d i e s

i n

B r i t a i n , u s i n g

d i e t a r y

h i s t o r i e s ,

a l s o

s h o w e d

n o c a s e - c o n t r o l

d i f f e r e n c e s .

C a s e - c o n t r o l

s t u d i e s

t h e r e f o r e

d o

n o t

p r o v i d e

c o n s i s t e n t

e v i d e n c e

t o

s u p p o r t

t h e

h y p o t h e s i s

t h a t l a c k

M

N e l s o n , J M o r r i s ,

  J P B a r k e r , a n d

S S i m m o n d s

o f d i e t a r y f i b r e i s a c a u s e

o f

a p p e n d i c i t i s .

F u r t h e r m o r e , a n a l y s i s

o f t h e t i m e t r e n d s

o f

a p p e n d i c i t i s i n B r i t a i n d u r i n g t h i s c e n t u r y d o e s n o t

s u p p o r t

a c l o s e

a s s o c i a t i o n w i t h

e i t h e r c e r e a l o r

v e g e t a b l e f i b r e c o n s u m p t i o n .

A r e c e n t c o m p a r i s o n

o f a c u t e

a p p e n d i c i t i s r a t e s

d u r i n g 1 9 7 8 - 8 2 a n d d i e t

i n 5 9 a r e a s

o f E n g l a n d

a n d

W a l e s r e v e a l e d n o c o r r e l a t i o n w i t h c e r e a l f i b r e i n t a k e

b u t a n e g a t i v e

c o r r e l a t i o n w i t h c o n s u m p t i o n

o f n o n -

p o t a t o

v e g e t a b l e s , p a r t i c u l a r l y g r e e n v e g e t a b l e s a n d

t o m a t o e s , a n d a p o s i t i v e c o r r e l a t i o n w i t h p o t a to

c o n s u m p t i o n .

  2

G r e e n v e g e t a b l e s a n d t o m a t o e s c o u l d

p r o t e c t a g a i n s t

a p p e n d i c i t i s t h r o u g h m e c h a n i s m s

a s s o c i a t e d

w i t h

f i b r e , w h o s e

c h e m i c a l c o m p o s i t i o n

d i f f e r s i n v e g e t a b l e s a n d c e r e a l s .

H o w e v e r , t h i s

p r o t e c t i v e e f f e c t h a s n o t b e e n r e v e a l e d i n a

c a s e -

c o n t r o l s t u d y i n o n e t o w n .

We a r e

g r a t e f u l t o t h e s t a f f

i n t h e P a e d i a t r i c

U n i t ,

P a t h o l o g y a n d M e d i c a l R e c o r d s D e p a r t m e n t s ,

S o u t h a m p t o n G e n e r a l H o s p i t a l , f o r t h e i r h e l p i n t h e

s e l e c t i o n o f c a s e s ; t o t h e h e a d t e a c h e r s i n

S o u t h a m p t o n

who

h e l p e d

w i t h t h e

s e l e c t i o n o f

c o n t r o l s ;

a n d t o o u r c o l l e a g u e s ,

P a u l W i n t e r a n d

C l i v e

O s m o n d ,

f o r

c o m p u t i n g

a n d s t a t i s t i c a l a d v i c e .

W i t h o u t t h e c o o p e r a t i o n

o f t h e c h i l d r e n a n d

t h e i r

f a m i l i e s ,

w h o

c o m p l e t e d

t h e

d i e t a r y r e c o r d s ,

h e

s t u d y

w o u l d

n o t h a v e b e e n

p o s s i b l e .

R e f e r e n c e s

 

R e n d l e S h o r t A .

T h e c a u s a t i o n o f a p p e n d i c i t i s .

B r J

S u r g

1 9 2 0 ;

8 : 1 7 1 - 8 8 .

2

B u r k i t t

D P . T h e

a e t i o l o g y

o f

a p p e n d i c i t i s .

B r J

S u r g

1 9 7 1 ;

5 8 : 6 9 5 - 9 9 .

3

B a r k e r

D J P .

A c u t e a p p e n d i c i t i s a n d

d i e t a r y

f i b r e : a n

a l t e r n a t i v e

h y p o t h e s i s .

B r

M ed J

1 9 8 5 ;

2 9 0 :

1 1 2 5 - 7 .

4

N e l s o n M ,

B a r k e r D J P ,

W i n t e r P D .

D i e t a r y

f i b r e a n d

a c u t e

a p p e n d i c i t i s :

a c a s e - c o n t r o l

s t u d y .

Human N u t r i t i o n :

A p p l i e d

N u t r i t i o n

1 9 8 4 ;

3 8 A : 1 2 6 - 3 1 .

C o v e - S m i t h J R L a n g m a n

M J S .

A p p e n d i c i t i s

a n d

d i e t a r y

f i b r e .

G u t 1 9 7 5 ;

1 6 :

4 0 9 .

6

G e a r J S S . E p i d e m i o l o g i c a l

s t u d i e s o f t h e r o l e

o f

d i e t a r y

f i b r e

i n

t h e

a e t i o l o g y

o f d i s e a s e .

T h e s i s ;

O x f o r d

U n i v e r s i t y

1 9 7 8 .

7

B r e n d e r J D ,

W e i s s

N S , K o e p s e l l

T D ,

M a r c u s e

E K . F i b e r

i n t a k e a n d c h i l d h o o d a p p e n d i c i t i s .

A m J

P u b l H l t h

1 9 8 5 ;

7 5 :

3 9 9 - 4 0 0 .

8

A r n b j o r n s s o n

E . A c u t e

a p p e n d i c i t i s

a n d

d i e t a r y

f i b r e . A r c h

S u r g 1 9 8 3 ;

1 1 8 : 8 6 8 - 7 0 .

9

N e l s o n

M .

A

d i e t a r y

s u r v e y

m e t h o d

f o r

m e a s u r i n g

f a m i l y

f o o d

p u r c h a s e s

a n d i n d i v i d u a l

i n t a k e s

c o n c u r r e n t l y ,

a n d i t s u s e

i n

d i e t a r y

s u r v e i l l a n c e .

Ph D

t h e s i s ,

L o n d o n

U n i v e r s i t y

1 9 8 3 .

0

S o u t h g a t e D A T , B a i l e y B ,

C o l l i n s o n

E ,

W a l k e r

A T .

A

g u i d e

t o c a l c u l a t i n g

i n t a k e s o f

d i e t a r y

f i b r e . J

H u m N u t r

1 9 7 6 :

3 0 : 3 0 3 - 1 3 .

B r e s l o w

N E ,

Day

N E . S t a t i s t i c a l

m e t h o d s

i n c a n c e r

r e s e a r c h .

V o l

1 . T h e

a n a l y s i s

o f

c a s e - c o n t r o l

s t u d i e s .

IARC

S c i e n t i f i c

P u b l i c a t i o n s n o . 3 2 .

L y o n

IARC 1 9 8 0 .

1 2

B a r k e r

D J P ,

M o r r i s

J ,

N e l s o n

M.

V e g e t a b l e c o n s u m p t i o n

a n d a c u t e

a p p e n d i c i t i s

i n

5 9 a r e a s i n

E n g l a n d

a n d

W a l e s .

B r

M ed

J

1 9 8 6 ;

2 9 2 :

9 2 7 - 3 0 .