1. Principal Investigator
Chest Radiographs and their reliability in the diagnosis of Tuberculosis
Principal Investigator
Dr. Narayan Kumar
T.B. Specialist & Hospital Director, BPKIHS
Co Investigators
Prof. S.K. Bhargava, Prof. Kuryan George, Prof. C.S. Agrawal, Dr. Prahlad Karki, Mr. Dharanidhar Baral, BPKIHS

4. Objectives
To see the reliability in diagnosis of tuberculosis by X-ray in context of our country doctor, radiologist, physicians of different level.

5. Material & Method
Study site:- Tuberculosis Clinic of the BPKIHS. A 700 bed teaching hospital.
Tuberculosis Lab Present with fluorescent microscopy and culture facilities.

6. Method 75 radiographs of following diagnosis
Sputum +ve
Healed tuberculosis
Pleural effusion
Non tuberculosis lung lesion
Healthy patient (normal CX)
The diagnosis was arrived after review by expert of panel which included
Radiologist
Surgeon
Physicians

8. Reference for panel was on the following basis:-
Radiological finding
Bacteriological finding
Response to anti TB chemotherapy
The diagnosis made by panel on above criteria was considered – the “Gold standard” for further analysis.

14. Qualification of doctor
MD Internal Medicine
MS General Surgery
MS Obs/Gynae
MD Radiodiagnosis
MBBS
Question
A format to locate the lesion
Diagnosis choice
Active TB
Inactive TB
Healed TB
Non tuberculous
Normal
The findings were compared against the gold standard.

19. Age-Gender distribution of 25 doctors.
Results
Age-Gender distribution of 25 doctors.
Age -group
In Years
Gender
Total
Male
Female
25-29
5(22.7)
3(100)
8(32)
30-34
11(50)
11(44)
35-39
2(9.1)
2(8)
40-44
45+ 22 3 25

20. Year of passing MBBS Year No. (%) <1970 2(8) 1970-1980 1(4)
5(20)
> 1990
17(68)
Total 25

21. No of Radiographs seen /day
by a doctor
No. of Radiographs/day
No.(%)
<=10
5(20)
11 –20
7(28)
>=21
2(8)
No response
11(44)
Total 25

22. Validity of Chest x-ray in diagnosing tuberculosis
Diagnosis by
Physician
True diagnosis
Total Tb
No Tb
1191
172
1363
334
178
512
1525
350
1875
Sensitivity : 78.1%
Specificity : 50.9%

23. Validity of Chest x-ray in diagnosing active tuberculosis
Diagnosis by
Physician
True diagnosis
Total Tb
No Tb
597
245
842
403
630
1033
1000
875
1875
Sensitivity: 59.7%
Specificity: 72%

24. Score of physicians in reading Chest Radiographs
Overall
(n=25)
Postgraduates
(n=13)
MBBS
(n=12)
Maximum 54 39
Minimum 22 33
Mean
35.8 36 32
Median 35 43
31.4

25. Physician’s diagnosis
Agreement between physician and radiologist
Diagnosis by
Radiologist
Physician’s diagnosis
Total
Correct
Wrong 34 20 54 9 12 21 43 32 75
K = 0.17(0-0.38)
*figures in parenthesis indicate the 95% CI

26. Conclusion Unsatisfactory sensitivity and specificity.
Taking a factor of 2% population have TB and 5% have symptoms of TB, the predictive value among the symptomatic will only be about 60% and negative predictive value 72%.
Physician would lead treating a large proportion of them unnecessarily.

27. Over diagnosis is followed by over treatment :- unmanageable burden on the health resources.
The low sensitivity could also lead to under diagnosis and consequently deny of chemotherapy.

28. NTC or other stake holders in program should focus the message to the mass that x-ray is not important as the patient himself belief that x-ray is essential and the doctor also believe therefore the problem is doubled till date NTC is giving message to doctor but not accepted by the doctor, there is no attempt to give message to population about this fact.