Notes on the tuberculin test

Tubercle, Lond., (r957), 38,259

Notes on the Tuberculin Test By W. A. GRIEP and M. A. BLEIKER

from the National Health Research Council, Holland In spite of the great volume of work already carried out on the technique and results of tuberculin testing, there are still many gaps in our knowledge. It is hoped that the following short notes about investigations carried out in Holland will be of some value in filling these gaps. Except where otherwise stated, the standard 5 TV PPD test was used throughout. The reading of the test was carried out by skilled observers. Sensitivity to Tuberculin in the Higher Age Groups There have been several investigations into the relationship between age and tuberculin sensitivity (Girard and Viallier, 1941; Levrat and others, 1941; Brodin and Forestier, 1943; Fourestier and Chatani, 1943; Andenaes, 1945; Coury and Marland, 1948; and Meyer, 1951). Their results agree in finding a decrease in the percentage of positive reactions in the older age groups. We have re-examined this question in a population of 1,392 persons selected at random from those called up for mass examination. Those with tuberculous lesions, unless they were calcified, were excluded. The results are shown in Fig. 1A and Fig. IB. It is seen that the percentage with positive reactions (greater than 5 rnm.) has a maximum between 50 and 60 and then decreases. In addition, the usual bimodal distribution disappears after 50. Some observers believe that the loss of sensitivity is due to complete healing of the tuberculous lesion (Saenz, 1940; Keller and Schomerus, 1951). Others believe that it is due to lack of reinforcement of the original infection. Continual new superinfections are, they believe, necessary to maintain the sensitivity (Troisier and Maclouf, 1942; Canetti, 1946). Still others believe that the change in the skin of old people is responsible (Valtis and Portret, 1937; Bariety and Brocard, 1950). To investigate the latter hypothesis we determined the tuberculin sensitivity in two groups of people of all ages, one with active tuberculosis and the other with a similar age distribution but without tuberculosis. We argued that the decreased reactivity of the skin - if it existed - should be demonstrable in the old people who had active tuberculosis. The results are shown in Tables I and II. All but 3 of the 361 patients with active pulmonary tuberculosis had reactions of 6 mm, or more; and these 3 were under 40 years old. The mean induration was approximately TABLE

MEAN INDURATION TO 5 TV TUBERCULOUS PATIENTS ACCORDING

I. -

Males Age (years)

I6-QO 213 14 15 16171-

Total

No.

Mean diameter (mm.)

6 41 46 28 29 14 3

12·8 12·8 12'5 12'4 13'0 12'5 11'7

167

PPD TO

AMONCl AGE

Total

Females

No. 15 89 46 27 6

6 5 194

361

Mean diameter

Mean diameter (mm.)

No.

(mm.)

12·8 12'4 12'4 12'5 14'0 14'0 I 1'4

21 130 92 55 35 20 8

12'8 12'5 12'5 12'5 13'1 12·8 U"5

361

~

,,,:B

264 pel":soD6

tLt-20year::s oF. age N 6mln. 15.5' %

=

~

J

m..anind. )/6mm= 11,4

~

173 perllon!>

184 per::son:S

216 pel"60n:s 21-30year60f .. ge

00

31-~OYe.... ~ .. fage

lneanind.}/6mm:12.9mm

mes"

f

-41-50yeao-.... age 6mm= 75",7%

)Y6mm= 66,9%

);6mm ="'B,~%

m"an incl. ~ 6mm:12,9,,"n .

;nd .),6mln:'12,2W1.ln

t<'I

32

30

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FIG. IA. - Distribution by size of induration of tuberculin tests with 5 TV PPD in 837 persons between the ages of 14 and 50 years.

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FIG. ra, - Distri buti on by size of ind uration of tubercu lin tests wi th 5 T U PPD in 555 p ersons over the age of 50. 10

...

en

26~

TUBERCLE TABLE

II. -

6 MM,

AND

MEAN INDURATION TO 5 TU PPD OF ALL REACTIONS OF MORE AMONG 1,392 PERSONS NOT SUFFERING FROM TUBERCULOS[S

Males Age (years) 16-20

z r3 1-

,p-

5[6[7 1-

8[ -

Total

Females

Mean diameter (mm,)

No. 135 96 79 83 68 54

49

12'1 12'8 12 '3 [3 '5 [2,6 12'1

1.29 120 105

Hl'4

101

10 '2

23

No.

5 87

~~

95

96

Total

Mean diameter (mm.)

No.

10,8

264

[ 1'4 12'9 12'2 12 '9 12'[ 12'6

216 184173 137 149 15° II9

IS 'O

12 '2 12'1 II

Mean diameter (mm,)

,8

IS'2 IS 'O

13'1

IS'I

12'5

I , S9 2

8 05

equal at all ages and very similar to the mean induration of those who did not have tuberculosis. This does not support the hypothesis that the changes in the skin are t he cause of the decreased sensitivity to intradermal tuberculin in older people, In addition to measuring size, the indurations were classified a ccording to density into four types (Type I being the firmest) (Edwards and others , 1953)' The results are shown in Tables III and IV. It will be seen that the indurations become weaker with age, and as this is the case in both groups it is probable that this is a property of the skin of old people. T A BLE HI. - DENSITY OF INDURATION (EDWARDS AND OTHERS, AMONG 358 TUBERCULOUS P AT IENTS, AaCO RDING TO AGE

DeTisiry Age (yeaTS)

if induration (per cel/t)

Type 1

Type 11

Type III

[6-20

4

21-

.2

85 85 88

13

!p-

I

4 15 161-

0 0 0

7[-

0

1955)

8S 70

45

36

Type IV 0 0 0 2

I I

II

17 24 5°

5

5~

12

6

TABLE IV. - DENSITY OF INDURA TION (E DWARD S AND OTHERS, 1955 ) TO 5 TV P P D AMONG PERSONS NOT SUl'FERlNG F ROM TUBERCULOSIS, ACCORDING TO AGE (ONLY INDURATIONS 01' 6 MM , AND MORE ARE INCLUDED)

DensilJl if induration(per cent) Age (years)

TyjM I

TyjJe II

Type III

Type IV

16-20 21-

0

2

6

9

3 14 1-

91 92

I I

88

0 0 0

5 1-

617 181 -

I

2 0

a

90

~~

45

SO

9 10 21 28

4

5°

5

61

[

2

9

2 63

THE TUBERCULIN TEST TABLE V, - PERCENTAGE 'POSITIVE' REACTIONS AND MEAN SIZE OF INDURATIONS TO 5 TV PPD ON 12 CONSECUTIVE DAYS AMONG 181 ADULT TUDER.CULOUS PATIENTS

Males

Females

Total

Mean Mean Mean Days before diameter 'Positive diameter 'Positive' diameter 'Positive' (mm,) reaction read (mm,) (mm,) % % % II'6 11,6 12'0 11'3 la'S 10'3 9'6 8'4 6'9 5'8

I

2 3 4 5 6 7 8 9 10

10'7 12'2 12'5 10'7 10'0 9'2 8'0 6·6 5,6 4'0 4'1 2'4

97'0 97"0 97'0 97'0 96'0 94'0 92'7 85'9 66'0 58'0

II

12

93'8 9 2'5 92'5 95'1 9 0'1 88'8 76'6 61 '3 54'5 3 6-7 3 8- 1 17"5

11'2 I I ,8 12'2 I 1'1 10'2 9,8 8'9 7,6 6'4 5'0 4'1 2'4

95'6 95'0 95'0 9 6'1 93'4 92'0

85'3 74'9 59'4 4 6'2 3 8'1 17'5

The Opflrrrum Time for Reading the Results of Intra-cutaneous Tuberculin Tests Some authors state that the correct time to read the test is on the third day (Mande, 1954), others on the second or third day (National Tuberculosis Association, 1950), and still others on the third or fourth day (Us tvedt, 1951). All assume that the later the reactions are read the fewer non-specific reactions will be included, The most accurate quantitative work in this respect is that done by the WHO Tuberculosis Research Office (1955)' It is claimed that non-specific reactions are at a maximum within twenty-four hours and decrease steadily after this. As, however, they used a I TU test and an Egyptian population, it seemed worth while repeating this work using the 5 TU test and a European population. Our work was carried out on 100 male and 81 female tuberculous patients who could therefore be expected to show a positive reaction. All the tests were read by one nurse on twelve consecutive days and she was kept ignorant of her previous readings. In addition to measuring the diameter, she classified the indurations according to density (Edwards and others, 1953). The results are shown in Fig. 2. The unimodal distribution is, of course, due to the fact that the population was a tuberculous one. If a reaction of more than 6 mm, is accepted as positive, it will be seen that the fewest negatives are found by reading on the fourth day. After the fourth day, the percentage of positives declines, Table V shows that the mean diameter of the induration is greatest on the third day in men as well as in women, and Table VI shows that the indurations are firmest on the third day, TABLE VI. - DENSITY OF TO THE INTRADERMAL 5 AMONG

Proportion of total readon consecutive days (per cent)

Density of induration Type Type Type Type

I II III IV

INDURATIONS (EDWARDS AND OTHERS, 1953) TEST (>6 MM.) ON 9 CONSECUTIVE DAYS 181 TUBERGULOUS PATIENTS

TV

2

3

2

2

2

38

32

51 47 0

66 4

60 6

4

5

6

7

8

2 46 46

0 35 53 12

0 26 62

0 10 67

12

23

0 2 54 44

6

9 a

a 22 78

TUBERCLE 60

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10

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FIG. 2. -

rlh

-

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,.day.2.

f-

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fl-

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hl.m. •

Distribution by size of induration on 10 consecutive da ys to in tradermal 5 TU test am ong Jar tuberculous persons.

THE TUBERCULlN TEST TABLE VII. - INTERPRETATION OF REACTIONS TO 5 TU ON THE FIRST SIX DAYS AMONG 181 ADULT TUBERCULOUS PATIENTS IF THE THIRD OR FOURTH DAY HAn BEEN AsSUMED TO BE THE 'IDEAL' DAYS FOR READING THE REACTIONS

'Ideal' dayfor reading the reactions

Dqy before reaction read

~

Third day

Fourth day

Percentage if 'False 'False negatives' positives'

Percentage of 'False 'False negatives' positives'

6 6

5 6

6 6

5

4 o

3 4 5 6

o

2

4 9

2

6 9

2

~

617 PER50N5 ~ \Jltnotll vetlve.s >16 ttun.: 26,~ % h:1ean >, 6mm.", 1~,a%

60 i\

'Wi ~h VQ lve e lt6mtn.=,,.,,8 % tn esn >;. 6 rn.tn:: 8,9 %

1'0 -4~

-40

q)

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...

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te\ .. ClC\fC'(C'(

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12. 16

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FIG. 3. - Distributions by size of reactions to intradermal 5 TV tests performed by syringes with and without valves.

266

TUBERCLE

2.35 PER50N5 '--

'Phy~.

::::::::

5" -r.u. "P:P.b.

Saline

.....

e40 t'o-

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FIG. 4. - Distributions by size of reactions to intradermal tests with 5 TU PPD and saline. Syringes with valves.

fo

0'1

2.J •

ml, physiological

In Table VII an attempt has been made to demonstrate the errors that would have been made had the test been read on days other than the 'ideal' day. In the first column it is assumed that the third day is the 'ideal', and in the second column the fourth day. It is clear that if the third day is correct, the fewest errors are made on the fourth, and if the fourth day is correct the fewest errors are made on the third. Tuberculin Tests Given with a Syringe with a One-way Valve All observers agree that there is always some reflux when the usual type of tuberculin syringe is used. This has some disadvantages, both in reducing the accuracy of the test and increasing the possibility of transferring infectious jaundice (Malmros and others, 1948; Hughes, 1946; Evans and Spooner, 1950; Dekking, 1951; Voorhorst, 1951; Hertzberger, 1953; Bruins Slot, 1953). To avoid this, a syringe with a one-way valve has been produced (Gispen, 1952; Gispen, 1954; Lebret and others, 1954); and this was used in the first place to test 1,641 males. The frequency distribution of the indurations was very different from usual. The usual bimodal distribution had disappeared, and there were very many more reactions of 3 to 6 mrn. diameter. To investigate this further, 617 young men were tested on both arms, using a normal syringe on one arm and a syringe with a one-way valve on the other. The results were all read by one observer who was unaware which test had been given by.whichsyringe. The results are shown in Fig. 3; and the difference in distribution caused by the one-way syringe is very clearly demonstrated.

THE TUBERCULIN TEST

To exclude the possibility that the valve itself, which was made of copper and rubber, was producing non-specific reactions, 235 young men were simultaneously tested on both arms. For one arm saline was used and for the other the usual 5 TU injection. In both cases, a syringe with a one-way valve was used. The results are shown in Fig. 4. It will be seen that the saline gives the usual distribution of nonspecific reactions, but the frequency distribution of the tuberculin reactions was again unusual. It is difficult to explain these results; but it seems probable that the syringe with the one-way valve injects tuberculin more slowly under lower pressure and that possibly less will escape into the subcutaneous tissue. It is possible, too, that the dosage is somewhat larger. All this, however, would suggest that the syringe with the one-way valve gives the 'correct' distribution and that the usual bi-modal distribution found with syringes without valves may be incorrect. However, from the practical point of view, the one-way valve syringe cannot be recommended. Those who were tested with this syringe had considerably more pain, and the technique of injection is more difficult. So we ourselves, in spite of the theoretical interest of these findings, have stopped using syringes with one-way valves. Sununary From the results of t uberculin surveys on large populations, evidence is presented: (i) confirming the reduced tuberculin sensitivity in older people. Further investigations suggested that the reduced area of the reaction is not due to age changes in the skin, but the reduced firmness might be. (ii) suggesting that tuberculin tests should be read on the third or fourth day. (iii) suggesting that the usual bimodal frequency distribution of reactions may not be the distribution of degrees of sensitivity, as it is abolished if a tuberculin syringe with a one-way valve is used. References

Andanaes, O. M. ( 19'fS) Acta where. scand., I9,21!. Bariety, M., and Brocard, A. (19S0) Reo. Tubere., Paris, 14,213. Brodin, P., and Fouresticr, M. (1943) Paris med., 51, 179. Bruins Slot, W. j. (1953) Ned. T ijdschr. Geneesk., 97, 1650. Canetti, G. (1946) L'Allergie Tuber culinque chez I'Homme, p. 338, FJammarion, Paris. Coury, C., and Marland, P. (1948) Paris med., 38, 262. Dekking, F. (1951) Ned. Tijdschr. Oeneesk., 95, 2114. Edwards, L. B., Palmer, C. E., and Magnus, K. (1953) BeG Vaccination, p. 33, World Health Organization: Monograph Series No. 12, Geneva. Evans, R. J., and Spooner, E. T . C . (1950) Brit. med. ] ., ii, 185. Fourestier, M., and Chatain, J. (1943) Rev. Tuberc., Paris, 8, 168. Girard, M., and Viallier,j. (1941) Lyon med., 165,329. Gispen, R. (I 952) Lancet, ii, 171, Gispen, R. (19S4) Int. Arch. Allergy, N.Y., 5, '152. Hertzberger, E. (1953) Ned. Tijdscbr. Geneesk., 97, 1906. Hughes, R. R. (1946) Brit. med, J., ii, 685. Keller, W., and Schomerus, E. (1951) ..c:. Tuberk., 97, 163. Lebrct, J. D., Tasman, A., and Gispen, R. (1954) Ned. Tijdscl«, Geneesk., 98, 136r. Levrat, M., Roche, L., and Pont, M. (1941) Lyon med., 165, 227. Malmros, H., Wilander, 0., and Herner, B. (1948) Brit. med. J., ii, 936. Mande, R. (1954) Manual Pratique de Vaccination par Ie B.C.G., Centre International de I'Enfance, Paris. Meyer, S. N. (1951) Puhl. Hlth. Rep., Wash., 66, I. National Tuberculosis Association. (1950) Diagnostic Standards and Classification of Tuberculosis, gth edit, New York. Saenz, A. (1940) PT. mtd. , 48, 955. Troisier, J., and Maclouf, A. C. (1942 ) Paris med., 32,289. Ustvedt, H. ]. (1951) In The Conference on European B.C.G. Programmes, p. 161, Heinemann) London. Valtis, J., and Portret, A. (1927) C.R . Soc. Biol., Paris, 97,345. Voorhorst, R. (19S1) Ned. Tijdschr . Geneesk., 95,2108. WHO Tuberculosis Research Office (19.55) Bull. World Hlth. Org., 12, r89. U