Nigerian Journal of Paediatrics

1Evaluation of the inner thigh as site for mantoux test among children in Owerri South Eastern Nigeria

Niger J Paediatr 2016; 43 (4): 236 – 239

ORIGINAL

Ezeogu J

Evaluation of the inner thigh as

Nwolisa E

Emechebe G

site for mantoux test among

Wammanda R

children in Owerri South Eastern

Nigeria

DOI:http://dx.doi.org/10.4314/njp.v43i4.1

Accepted: 30th July 2016

Abstract : Background: Mantoux

standard, values of inner thigh

test, a type IV hypersensitivity

induration at a set cut-off was de-

Ezeogu J

(

)

reaction, is commonly used to

termined. Students’t test, Pearson

Nwolisa E

screen children for possible tuber-

correlation coefficient and the Chi

Department of Paediatrics,

Federal Medical Centre Owerri, Nigeria

culosis. It is applied on the volar

square were used to compute data.

Email: jezeogu@yahoo.com

surface of forearm. Sunlight ultra-

Results: The mean diameter of

violet rays (UV) have recently

induration on the inner thigh

Emechebe G

been shown to induce immuno-

(12.51 ±3.44mm) was higher than

Department of Paediatrics and Child

suppression that alters the skin

mean diameter of induration on the

Health, Imo State University Teaching

response to Mantoux test nega-

volar

surface

the

arm

Hospital Orlu Imo State Nigeria

tively.

(11.03±6.34mm). This is however

Objective: The study aimed to

not statistically significant. There

Wammanda R

evaluate the inner thigh as a possi-

were (29) children who had reac-

Department of Paediatrics,

Ahmadu Bello University Teaching

ble site for Mantoux test in chil-

tive induration on the inner thigh

Hospital Zaria Kaduna State Nigeria

dren attending Federal Medical

whilst 19 had similar induration on

Centre Owerri whom their pri-

the volar surface of the forearm. In

mary attending Physicians re-

the presence of factor(s) that nega-

quested a Mantoux test.

tively affects the response of the

Methods: This was a cross sec-

skin to Mantoux test; the inner

tional study conducted between

thigh induration yield was higher.

June and October 2011. Concomi-

There was a strong positive corre-

tant intradermal injection of 0.1ml

lation between the two site meas-

of purified protein derivative on

urements.

the volar aspect of the forearm

Conclusions: The inner thigh as a

and the inner thigh was carried

site for Mantoux test in children

out. Induration was measured

has shown potential for higher

concurrently in 106 consecutive

yield.

children, between the ages of

3months and 15 years. Using

Keywords: Sunlight, Inner thigh,

volar surface of forearm as gold

Mantoux test, TB, Children.

Introduction

tect children and adolescents with latent TB infection. It

is applied on the volar surface of the forearm (for ease of

The diagnosis, treatment, and prevention of tuberculosis;

assessing the presence or absence of induration). Man-

is made difficult by the huge challenge of worldwide

toux test may be affected negatively by such factors as

severe malnutrition, steroid, and cytotoxic therapy.

3,4

human immunodeficiency virus (HIV) pandemic. Early

and accurate tuberculosis diagnosis is essential to im-

Immunosupression induced by ultraviolet rays (UVR)

prove treatment outcomes for patients. In the diagnosis

has been shown to alter the skin response to the Man-

toux test negatively.

5-9

of childhood TB, a criteria based on clinical and radio-

Furthermore, It has been ob-

logical findings have been developed by the World

served that even modest doses of UV rays can signifi-

Health Organization (WHO).

1,2

The laboratory diagnosis

cantly reduce local delayed type IV hypersensitivity

of tuberculosis involves culture of sputum and other

(DTH) response to recall antigens, and that recent sun

clinical specimens in Lowenstein-Jensen medium, Ziehl-

exposure should be considered a possible cause of false

negative Mantoux response.

Neelsen staining for acid fast and alcohol fast bacilli,

Lipoarabinomannan detection assay, Microscopic obser-

Kuchel and Barnetson documented a clear reduction in

vation of drug susceptibility assay, Quanti FERON-TB

Gold and Mantoux test. In the less developed countries

the Mantoux response at UV irradiated site when com-

of the world, screening of children for possible TB is by

pared to the un-irradiated site. They suggested the use of

tuberculin skin testing. Mantoux test is expected to de-

the lower back; a part of the body not exposed to

237

sunlight UVR as site for Mantoux testing, especially for

was differentiated with an ink marker, using a circle

children in the tropics who are exposed to enormous

about 2-4 centimetres diameter with the site of the injec-

amount of sunlight.

tion in the centre. The parents and subjects were advised

Recently, Wammanda et al in a study in Zaria Nigeria

not to stroke or sponge the injection site during a bath

highlighted the potential for an enhanced Mantoux test

(to avoid false positive results), and to have the children

result if parts of the body that are not exposed to high

dressed in clothes that will cover the thigh (to remove

doses of ultraviolet radiation are used.

exposure to UV light that may lead to a false negative

This cross sectional study which was aimed at evaluat-

result).

ing the inner thigh as a potential site for Mantoux test in

The sites for Mantoux test were examined for the pres-

children was undertaken in Owerri South Eastern Nige-

ence or absence of induration after 48-72 hours. In sub-

ria. Mantoux test was requested for suspected TB cases

jects with induration, it was measured along the trans-

verse axis of forearm and thigh in millimeters

as part of their evaluation for tuberculosis by their pri-

with a

mary attending physicians.

transparent meter rule, using the ball point pen technique

Reading was done in good light by a re-

of Sokal.

searcher. To be regarded positive, induration ought to

measure ≥10 mm.

Materials and Methods

Statistical analysis

This cross sectional study was carried out at the Federal

Medical Centre, Owerri (FMCO) a tertiary Health facil-

The collected data was analysed using the Statistical

ity in Imo State, South Eastern Nigeria. It was carried

Package for Social Sciences (SPSS) for Windows (Inc.

out from June to October 2011. One hundred and six

Chicago USA, 2001). Paired t test was used to compare

children were studied, their age ranged from 3 months to

the mean induration measurements from the two sites.

15 years. Sample size was calculated using prevalence

Correlation was determined by the Pearson correlation

from a previous study in Owerri

coefficient. The level of significance was taken to be

Ethical approval was sought and obtained from Ethics

p<0.05.

Committee of the Federal Medical Centre. Parents/care

givers of the subjects gave informed consent before in-

clusion in the study. However, any subject that violated

the protocol at any point during the course of the study

Results

or those on cytotoxic, steroid therapy at least 6 week

before enrolment were excluded.

The subjects’ age ranged from 3 months -15 years. Out

of the 106 children, 60 (56.6%) were male while 46

A structured interviewer administered questionnaire was

(43.4%) were female with a male/female ratio of 1.3:1.

used to obtain pertinent socio-demographic and clinical

The mean age was 6.5 ± 4.2 years. Of the 106 studied

information.The height in centimetre (cm) and weight in

children, 85 (80.2%) had normal weight for age while

kilograms (Kg) of subjects was measured using appro-

11 (10.4%) were underweight for age, none of which

priate equipments (An infantometer and a stadiometer to

was overtly malnourished. The overweight for age chil-

which a weighing scale (ZT-120 Health scale) was at-

dren were 10 (9.4%).There was a progressive increase in

tached). For the very young children less than 2 years

the number of inner thigh induration measurements with

old, lengths were measured using an infantometer with

increasing age, but among those 15+ years there was a

the help of an assistant. Elimination of zero error was

reduction in percentage of induration measurements.

This was statistically significant. χ =12.89, p=0.012

done before each weight was obtained. For older chil-

dren, weight and height were measured using a stadi-

(p<0.05).

ometer to which a weighing scale (ZT-120 Health scale)

was attached. Standardization using standard weights

The diameters of induration of the Mantoux response on

was done at intervals. A straight adjustable wooden

the volar aspect of the forearm for all studied children

blade was used as a headpiece to mark off the child's

ranged from 0-26 mm, (mean 4.15±5.72mm) while the

height. The results of height and weight were compared

diameters of the Mantoux response on the inner thigh

with the standard National Centre for Health Statistics

ranged from 0-22 mm (mean 4.91±5.64mm).This differ-

Charts (NCHS charts).

ence in mean was significant statistically, t=2.48, p

value=0.015. (p<0.05).

A dose of 0.1ml PPD (BB-NCIPD Ltd, Sofia, Bul-

garia), containing five tuberculin units constituted

The mean induration measurement on the volar surface

shortly before use; was concurrently administered in-

of the forearm (12.51 ±3.44mm) was not statistically

tradermally over the volar aspect of the forearm and the

significantly higher than the mean Mantoux induration

inner thigh (one finger breath medial to the spatial line

measurements on the inner thigh (11.03±6.34mm).A

running down the middle of the thigh). This was done

total of 29 (27.4%) children had positive Mantoux test.

using a 27 gauge needle by the principal investigator

In all the 29 (27.4%) children with a positive Mantoux

with an assistant after training and standardization of the

induration, the mantoux test was positive on the inner

process. Throughout the data collection process stan-

thigh, while in 19 (17.9%) of these subjects the con-

dard aseptic procedure was observed. The injection site

comitant Mantoux induration was positive (induration of

238

≥10mm) on the volar surface of the forearm. This differ-

Fig 3: The relationship between volar surface and inner thigh

ence in the site of Mantoux positivity was statistically

measurements.

significant.The average difference between the mean of

volar surface and inner thigh was 1.47 ± 7.10mm.

When the nutritional status was considered, 85 had nor-

mal weight for age,11 were underweight and 10 over

wieght. Of the 11 underweight subjects, 3 (27.3%) had

positive Mantoux induration on the inner thigh as

against 2 (18.2%) subjects with positive Mantoux indu-

ration on the volar surface of the forearm

The regression analysis of induration and weight among

subjects with induration showed that the ability of the

weight to predict the Mantoux response for the inner

thigh was p-value 0.412, beta-value 0.168, while for the

volar surface of the forearm p-value was 0.074 and beta-

value 0.357 (Figures 1 and 2).

Fig 1: Regression analysis of inner thigh induration and

weight among subjects withinduration. The ability to predictre-

Discussion

sponse for the inner thigh wasp-value 0.412, beta-value 0.168.

This study has demonstrated the potential of the inner

thigh as a site for an enhanced reactive Mantoux test

result in children. The number of children with reactive

induration on the inner thigh was higher (32%) than the

number of children with similar induration on the volar

surface of the forearm (12.3%). Even when ≥ 10 mm is

taken as cutoff for positive Mantoux induration, the

number of children with reactive induration of ≥ 10 mm

on the inner thigh was higher (27.4%) than the number

of children who had similar reactive induration on the

volar surface of the forearm (17.9%). This difference

Fig 2: Regression analysis of volar surface of forearm indura-

was statistically significant. A similar result was ob-

tion and weight among subjects with induration. The ability to

tained by Moyal, Kuchel, Damian and Wammanda

predict response for the inner thigh was0.074 and beta-value

0.357.

et al when they examined Mantoux induration measure-

Childs Weight (kg)

ments without a set cutoff point. Since the Mantoux tests

on the inner thigh and the volar surface of the forearm

were concurrently applied, the most likely explanation

for this observed difference would be the presence of a

factor that could negatively influence the delayed type

of hypersensitivity reaction in the children in a differen-

tial way. While malnutrition, steroid and cytotoxic ther-

apy will result in global immunosuppression in a child,

sunlight-induced immunosuppresion will depend on the

exposure of the skin to sunlight. Several other authors

9,10,14

have also previously documented the role of UV

light in significantly reducing local DTH response to

recall antigen.

Apart from the rate of reactive Mantoux response, this

A significant positive correlation between volar surface

study has shown that the mean diameter of the reactive

induration measurement and the inner thigh induration

Mantoux test was statistically significantly higher; when

measurement (r = 0.71; p<0.001) was established. As

the Mantoux test was applied on the inner thigh com-

shown in Figure 3, high volar surface measurements

pared to that obtained on the volar surface of the fore-

were associated with high inner thigh Mantoux measure-

arm. The mean inner thigh induration measurement was

ments.

higher than volar surface induration measurement with a

difference of 1.47 ± 7.10mm. This difference though

small and not statistically significant is critical when

measuring Mantoux induration in the children, where

accuracy is crucial for important management decisions

especially in tropical countries with dearth of facilities.

The result of this study also revealed that the use of the

inner thigh as a possible site for the Mantoux test may

239

be more appropriate than the volar surface of the fore-

number of children with similar induration on the volar

arm, the traditional site for this test, in situations where

surface of the forearm. Also in the presence of factor

the presence of factor(s) that negatively affects the re-

that negatively (underweight) affects the response of the

sponse of the skin to Mantoux test prevail. Out of the 11

skin to Mantoux test, the inner thigh as a site for PPD

children who were underweight at the time of the study,

administration in children has been shown to have good

3(27.3%)had positive induration. All the 3(27.3%) chil-

potential. Additional studies will be needed to further

dren had positive induration on the inner thigh as against

evaluate its benefit in the community especially in re-

1(9.0%) who had positive reaction on the volar surface

source poor countries.

of the forearm. Since the number of this group of chil-

dren was small, the statistical significance of this differ-

ence was not assessed. But the result suggest more reac-

Conflict of interest: None

tive Mantoux test result on the inner thigh compared

Funding: None

with the traditional volar surface of the forearm in chil-

dren who are underweight. This observed difference was

also highlighted by the Zaria study.

A limitation of this study was that it was a hospital

Acknowledgement

based study and therefore it will be hard to generalize

the result except a community based study is carried out.

We are grateful to the children and their parents/

guardians for participating in this study. The primary

attending Physicians and staff of the Chest unit of Fed-

Conclusion

eral Medical Centre Owerri are appreciated for their

contributions.

It is concluded that a higher number of subjects had re-

active induration on the inner thigh

compared to the

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