|Year : 2016 | Volume
| Issue : 1 | Page : 15-19
Radiographic evaluation of lateral chest wall soft-tissue thickness in adult pulmonary tuberculosis patients in Zaria, Nigeria
MZ Ibrahim1, ND Chom1, AU Hamidu1, MO Atalabi2, Inah Grace3, AM Tabari4
1 Department of Radiology, Ahmadu Bello University/Ahmadu Bello University Teaching Hospital, Zaria, Kaduna State, Nigeria
2 Department of Radiology, University College Hospital, Ibadan, Oyo State, Nigeria
3 Department of Radiology, University of Calabar Teaching Hospital, Cross Rivers State, Nigeria
4 Department of Radiology, Bayero University/Aminu Kano Teaching Hospital, Kano, Kano State, Nigeria
|Date of Submission||22-Jun-2015|
|Date of Acceptance||25-Sep-2015|
|Date of Web Publication||12-Feb-2016|
M Z Ibrahim
Department of Radiology, Ahmadu Bello University/ABU Teaching Hospital, Zaria, Kaduna State
Background: Pulmonary Tuberculosis (PTB) has high morbidity and mortality. It kills an estimated 2-3 million people a year with 95-98% of this mortality in developing countries. Nigeria ranks 4 th among 22 high burden countries in the world. It is associated with marked weight loss which can be evident at the lateral chest wall soft tissue thickness on the chest radiographs. Objectives: To compare the lateral chest wall soft tissue thickness on the chest radiographs of normal adult subjects and pulmonary TB patients in Zaria, also to determine sex difference in the lateral chest wall thickness in aforementioned subjects. Methodology: This prospective study was conducted over a six month period at the Radiology Department of Ahmadu Bello University Teaching Hospital, Zaria. Two hundred adults who were bacteriologically proven to have pulmonary tuberculosis were consecutively recruited into the study as cases. The same number of age and sex matched healthy individuals that had chest radiograph grossly normal were recruited as controls. Their lateral chest wall soft tissue thickness (subcutaneous fat and muscle layers) on the chest radiographs was measured. Results: A total of 400 patients, aged 18 to 70 years. Average age was 39.12 ± 11.89years.They were 135 (62.5%) females and 65 (37.5%) males The mean and standard deviation obtained for pre-treated PTB patients and control group were 12.66 ± 2.63 mm and 19.37 ± 2.65 mm respectively, and the difference was statistically significant (P < 0.0001). However, no significant increase is noted in lateral soft tissue thickness among different sexes. Conclusion: The lateral soft tissue thickness (muscle and fat) was generally lower in PTB patients compared to the healthy individuals.
Keywords: Chest radiograph, lateral chest wall soft-tissue thickness, normal adults, pretreated pulmonary tuberculosis patients
|How to cite this article:|
Ibrahim M Z, Chom N D, Hamidu A U, Atalabi M O, Grace I, Tabari A M. Radiographic evaluation of lateral chest wall soft-tissue thickness in adult pulmonary tuberculosis patients in Zaria, Nigeria. Sub-Saharan Afr J Med 2016;3:15-9
|How to cite this URL:|
Ibrahim M Z, Chom N D, Hamidu A U, Atalabi M O, Grace I, Tabari A M. Radiographic evaluation of lateral chest wall soft-tissue thickness in adult pulmonary tuberculosis patients in Zaria, Nigeria. Sub-Saharan Afr J Med [serial online] 2016 [cited 2019 Oct 16];3:15-9. Available from: http://www.ssajm.org/text.asp?2016/3/1/15/176298
| Introduction|| |
Pulmonary tuberculosis (PTB) is re-emerging with high morbidity and mortality in patients afflicted by it.  Tuberculosis (TB) kills an estimated 2-3 million people a year. It is estimated that between the years 2000 and 2020, nearly 1 billion people will be newly infected, 200 million people will get sick, and 35 million will die from TB if control is not further strengthened.  For this reason, the World Health Organization declared TB a global public emergency.  Nigeria ranked the fourth among the 22 high burden countries in the world and had the highest number of new cases in Africa, in 2009, with over 300 case/100,000 populations. 
Weight loss result in a reduction in the soft-tissue thickness (subcutaneous fat and muscle layer) of the lateral chest wall in patients with advanced/chronic PTB and other wasting diseases.
However, only two studies were conducted globally both in South Western Nigeria, which necessitated the need for this study in Northern Nigeria for comparison with the previous studies. This may lead to establishing a nomogram for lateral chest wall soft-tissue thickness in our locality.
The purpose of this study is to find out any definite or significant reduction in the lateral chest wall soft-tissue thickness of adult patients with chronic PTB when compared with healthy controls and to determine if there are sex and age difference in the lateral chest wall thickness in aforementioned subjects.
| Materials and Methods|| |
This cross-sectional descriptive study was carried out over a period of 6 months between July 2012 and January 2013 at the Ahmadu Bello University Teaching Hospital (ABUTH), Zaria in Northern Nigeria. The study population included individuals aged between 18 and 70 years that presented to the Radiology Department of ABUTH for chest X-ray. The study subjects were randomly selected from adult patients attending the pulmonary clinic who had been referred for chest X-ray on the basis of bacteriologically proven (acid-fast Bacillus + ve sputum) PTB. The control subjects were apparently healthy adults aged 18-70 years that attended GOPD and sent for routine chest X-ray for medical examination for school admission, visa application, or employment and had a radiologically normal chest radiograph. These control subjects were matched with the study subjects based on age and sex.
Inclusion criteria for PTB subjects were patient whose age ranges from 18 to 70 years and has been bacteriologically proven to have PTB; while those excluded were patients with extra-PTB, PTB patients with coexisting debilitating illnesses such as diabetes, malignancy and HIV infections, any patient who is already receiving anti-TB treatment, and those below 18 years or above 70 years of age.
The inclusion criteria for control subjects included apparently healthy persons aged 18-70 years who came for routine chest X-ray for medical examination for admission, visa application or employment, and who had a radiologically normal chest radiograph. Subjects suffering from any form of chronic medical condition or wasting diseases such as HIV/AIDS, poliomyelitis, cancers and lymphomas, as well as those with basic metabolic index of >25 kg/m 2 (overweight) or <18.5 kg/m 2 (malnourished), were excluded from the control group.
The minimum sample size was determined using Epi Info statistical software version 3.4 (CDC Atlanta Georgia USA 2011 (Centre for Disease Control)).  Adapting a national case detection rate of 20% in bacteriologically confirmed PTB cases,  a 95% confidence level and a statistical power of 80%, the minimum sample size for study group versus control at ratio 1:1 was derived as 44:44. However, for increased sensitivity of study and to allow for easy cross-tabulation to establish a relationship between variables,  a sample size of 200 was used for cases and the same number for control. Thus, a total of 400 subjects were recruited for the study.
The approval of the Ethics and Research Committee of ABUTH, Zaria and informed oral and written consent of the participants were obtained.
Standard posterior-anterior (PA) chest radiographs were taken for each of the subject population, and the soft-tissue thickness (comprising of the skin, subcutaneous fat, and the muscle layers) in the lateral chest wall was measured with the aid of hand-held ruler perpendicular to the radiopaque 10 th posterior rib and radiolucent fat pad at the so-called junctional zone or the "no - man's land," i.e., the area between the thorax and abdomen, as described by Lagundoye and Reddy.  This is an area in which the soft tissue runs parallel to the lower ribs about the level where the 9 th and 10 th posterior ribs make their final curvature forward from the posterior axillary line.  The average of the measurements of the two sides (right and left for comparison) was recorded in millimeter (mm).
Data obtained were entered into Statistical Package for Social Sciences (SPSS) software version 17.0 and analyzed. (INDUS Nomi, December 2008 IBM Chicago, USA). Mean and standard deviation were computed for the measured lateral soft-tissue thickness of PTB and healthy individuals (control). Similarly, mean and standard deviation of subject's lateral soft-tissue thickness were calculated for each age group. Student's t-test was used to determine the relationship between lateral chest wall soft-tissue thickness and sex. The relationship between measured lateral chest wall soft-tissue thickness and age was determined using one-way ANOVA test. The statistical test significance was taken P ≤ 0.05.
| Results|| |
A total of 400 subjects were recruited for this study, comprising of 200 PTB patients and an equal number of age- and sex-matched healthy individuals. Among the PTB patients, 135 (67.5%) were females and 65 (32.5%) were males with mean age of 39.19 ± 11.89 years. Majority of the patients were young females, within the age group of 31-40 years [Table 1].
|Table 1: Cross-tabulation of lateral chest wall thickness of pulmonary tuberculosis patients with age/sex matched controls|
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[Figure 1] and [Figure 2] show the planes of measurement for soft-tissue thickness of lateral chest wall in sketch diagram and PA chest radiograph, respectively. [Table 2] shows the measurement of lateral chest soft-tissue thickness and the values obtained from healthy individuals; while [Figure 3] shows similar measurement in PTB patient. The normal (mean value) lateral chest soft-tissue thickness of healthy individuals (control) was found to be 19.25 ± 2.54 mm. In addition, the maximum recorded lateral soft-tissue value was in the age of 51-60 years while the minimum lateral chest soft-tissue thickness was recorded in the age of ≤20 years. There was a significant increase in the recorded muscle thickness with increase in age in normal healthy individuals with a peak at 51-60 years (P = 0.007). However, the mean values of the subcutaneous fat and total lateral chest soft-tissue thickness were found not to be statistically significant in healthy subjects (P = 0.701 and P = 0.177, respectively).
|Figure 1: Chest radiograph sketch of the two component layers (A and B represent subcutaneous fat and muscle layers, respectively) making up the total soft-tissue thickness (T) of lateral chest wall in healthy subjects|
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|Figure 2: Frontal chest radiograph shows lateral chest wall soft-tissue thickness in healthy (control) adult. Key: Thick arrow on the right side = total lateral chest soft-tissue thickness (fat and muscle), thin arrow on the left side = muscle thickness in between arrowhead, and thick arrow on the left side = fat thickness|
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|Figure 3: Frontal chest radiograph showing pulmonary tuberculosis patient with lateral chest wall soft tissue wasting with thin (radiopaque) muscle and fat thickness represented by two arrowheads on the left side|
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|Table 2: Age group distribution in relation to total lateral soft-tissue thickness in healthy individuals|
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[Table 3] shows the recorded lateral soft-tissue thickness in pulmonary TB patients. It was found to be 12.66 ± 2.63 mm. The maximum mean value of lateral soft-tissue thickness was recorded in the age 51-60 years.
|Table 3: Total lateral soft-tissue thickness in relation to age groups among pulmonary tuberculosis patients|
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| Discussion|| |
Majority of the subjects studied were females in the age range of 31-40 years, which accounted for 44 out of 66. This is probably because a large number of female PTB patients within this age brackets have good health seeking behavior, and more female healthy subjects were newly employed staff in the control group.
In addition, PTB is commonly seen in the reproductive age group 18-59 years in a study by Leung  and William  in the USA. Nwanko et al.  also found a high prevalence of PTB among 21-30 years in Kano, Nigeria. Chigbu and Iroegbu  recorded the high prevalence of PTB patients within 18-50 years of age in Aba, Eastern Nigeria. This was similar to what was recorded by Oladigbo in 2004,  where she studied 203 PTB children and adult, and found an age range of 11-40 years with mean age of 29.69 years. These findings are similar to the finding in this study, and may be due to the fact that this age group of young- and middle-aged able-bodied persons are more exposed to the PTB risk factors in the environment. 
Nwachukwu et al. recorded higher in males PTB patients than females in Abia, Nigeria. Obi et al.  and Kolappan and Gopi  also found male predominance than females in Ebonyi and India, respectively. However, this is in contrast to, this study where more female PTB patients than male were recorded. In addition, women are presumably bonded with the stress of monthly menstruation, pregnancy, and lactation which may probably weaken their immune status and make them susceptible to infection by reactivating a quiescent PTB infection.
This study assessed the lateral chest soft-tissue thickness which comprised of muscle and subcutaneous fat thickness as seen on plain chest radiograph to evaluate wasting in PTB similar to the methods adapted by Lagundoye in 1974  in pediatric patients with kwashiorkor and Oladigbo in 2004  at Ile-Ife in PTB patients.
Oladigbo recorded a higher mean value for muscle, fat, and total soft-tissue thickness for PTB patients which were higher as compared to the corresponding measurements obtained in this study. The low socioeconomic status and high prevailing poverty in Northern Nigeria in comparison to the South where the previous studies were carried out could explain the much lower soft-tissue thickness recorded in this study.  However, both studies showed marked fat tissue thickness loss in PTB patients.
Lagundoye and Oladigbo's studies revealed that in children with kwashiorkor and in adults with PTB, respectively, the reduction in fat thickness outpaced that of muscle thickness. This is similar to the corresponding measurements obtained in this study.
The lateral chest soft-tissue thickness in the control group recorded by Oladigbo (2004) was higher than what was recorded in this study. This is likely due to the fact that overweight and obese subjects were not excluded from the previous control group, whereas those subjects were excluded in this study.
In general, there was significant reduction in the lateral chest wall soft-tissue thickness recorded in PTB patients in comparison to age/sex matched healthy adult individuals (P < 0.001). It is likely due to a reduction in appetite, leading to a decrease in energy intake and altered metabolism as part of the inflammatory and immune response. 
| Conclusion|| |
The lateral soft-tissue thickness (muscle and fat) was generally reduced in patients with PTB as compared to the healthy individuals (control), and no significant difference noted in comparison to age and sex of the PTB patients. The clinical implication of this study is that the lateral soft-tissue thickness of the lateral chest wall can be used as an index for evaluating wasting on chest radiographs in PTB patient, especially in complementing weighing scale as a tool for the assessment of weight loss.
A follow-up study of pulmonary tuberculosis patients after completing anti-TB medication should be advocated to assess the lateral chest wall soft-tissue thickness changes which can be implored as a follow-up tool for assessing response to therapy by serial chest radiographs.
Financial Support and Sponsorship
Conflicts of Interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]