IJCRR - 6(10), May, 2014
Pages: 45-50
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SPOT AND EARLY MORNING SPUTUM REPORT STUDY FOR DIAGNOSIS OF PULMONARY TUBERCULOSIS AT DMC OF MEDICAL COLLEGE VADODARA, GUJARAT: A RETROSPECTIVE ANALYSIS
Author: Meghna M. Patel, Apurv N. Patel, Jitendra A. Sisodia, K. R. Patel, Kalpita Shringarpure
Category: Healthcare
Abstract:Tuberculosis, caused by Mycobacterium Tuberculosis is a major public health problem. India is the highest tuberculosis burden country across the globe. Under the Revised National Tuberculosis Control Programme (RNTCP) diagnosis of pulmonary tuberculosis is done by sputum smear microscopy using Zeil-Nelson staining method. For sputum microscopy, two sputum (spot and early morning) samples are collected. Spot sample is collected at the time of first visit of patient to laboratory and early morning sputum is collected the next day. This study is based on retrospective analysis of spot and early morning sputum microscopy samples tested in the year 2012 and 2013 at Designated Microscopy Center (DMC) of Government Medical College, Vadodara, Gujarat. This study showed that the observed difference in sputum sample positivity in the two groups, viz. spot sample and morning sample in diagnosis of TB is statistically insignificant (Chi-square value 1.703 and 0.00584 respectively, P value 0.191 and 0.939 respectively).
Keywords: Tuberculosis, Sputum microscopy, Spot sputum, Early morning sputum
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INTRODUCTION
Tuberculosis (TB) is an infectious disease caused by Mycobacterium Tuberculosis. It typically affects the lung but also affects the other systems as well (Extra-pulmonary TB). In 2012 there were an estimated 8.6 million incidents case of TB and 1.3 million people died from the disease globally1 . India is the highest TB burden country with WHO statistics giving the total incidence of 2.2 million case of TB out of a global incidence of 8.7 million cases and an estimated TB prevalence of 3.1 million (2011). It is estimated that 40% of Indian population is infected with TB2 . Infectious sputum-positive TB patients with pulmonary disease produce droplet nuclei through coughing, sneezing and talking. It is estimated that one infectious case, on an average, infects about 10 -15 new cases every year. The concentration of bacilli in the sputum of a TB case correlates well with the infectivity of the TB patient. This is the reason why smear microscopy is a sensitive tool for identifying infectious cases and it is used as the mainstay diagnostic tool for tuberculosis control in India3 . In 2011, the new sputum positive (NSP) case detection rate was 71% and treatment success rate was 87%. Quality assured sputum smear examination facilities are available through more than 13,000 Designated Microscopy Centers (DMCs) across the country. The new vision of
RNTCP under the next five year plan (2012-2017) is of a TB free India and for achieving this vision, one of the targets is early detection and treatment of at least 90% estimated TB cases in the community including HIV-associated TB4. The older RNTCP guidelines required examination of three sputum specimen (spot-early morning -spot) by Zeil-Nelson (Z-N) stain for acid fast bacilli over two consecutive days. From 1st April 2009, under RNTCP two sputum specimens are collected over one, or two consecutive days. Of the two sputum specimens, one is collected on the spot and the other is an early morning specimen collected at home by the patient5 . The spot sample is collected at the first visit at laboratory and for the second early morning sample, sputum container is given to the patient, who collects the sputum early in the morning and submits it to the laboratory. Microscopy services currently require patients to make repeat visits to the healthcare facility. This is associated with considerable patient costs and patient drop-out during diagnosis. The new WHO definition of a smear positive case does not require confirmatory smears. This allows patients to be diagnosed on the basis of a single smear6 . A two day visit of patients to the health facility affects patients’ daily wages. Many patients do not come for submitting second early morning sputum sample due to cost, job related issues or due to some other reasons. Patients have to spend time and money behind it. Because of this, many patients remained undiagnosed and untreated. Undiagnosed and untreated sputum positive TB cases are the source of infection in community3 . If two sputum examinations are done on the first day of visit, it will reduce the number of visits and patient dropout rate. Objective To compare the sensitivity and specificity of spot and morning samples versus spot+ morning sample.
MATERIALS AND METHOD
This retrospective analytic study was carried out in Department of Pulmonary Medicine, based on sputum samples collected at DMC of Medical College, Baroda. In this study retrospective analysis of spot and early morning sputum sample result was done. At DMC, Sputum sample examination is done by Z-N stain for AFB and laboratory register is maintained as per RNTCP guidelines7 . Data of sputum examination results was collected from laboratory register of DMC for calendar year 2012 and 2013. In the laboratory records, spot sample is registered as sample A and early morning sample as sample B. As per RNTCP guide line if one sample out of two is positive then it is labeled as sputum positive5 . Inclusion Criteria: Data of sputum examination of both spot and early morning samples was collected from register. Exclusion Criteria: Record of sputum examination in which either spot or early morning result was missing were excluded in data collection. Statistical methods The sensitivity, specificity, positive predictive value, negative predictive value of two samples was calculated. Test of association between spot and early morning sample was done using ChiSquare test.
ESULTS
In 2012, total 5331 TB suspects were examined and amongst them 1017 were found to be positive and 4314 were negative. Out of total 1017 positive cases , total number of patients with both spot and early morning positive sputum report were 924, only spot positive were 20 in number and only early morning positive were 73 in number [Table 1 and 2]. Spot sample when compared with spot plus early morning sample gave sensitivity of 92.67%, specificity 100.16%, positive predictive value 97.88%, negative predictive value 98.33%. While early morningsample when compared with spot plus early morning sample gave sensitivity of 97.88%, specificity 98.33%, positive predictive value 92.67%, negative predictive value 99.53%. In 2013 total 5495 TB suspects were examined and amongst them 937 patients were found to be sputum positive and 4541 patients were sputum negative. Out of total 954 positive cases , total number of patients with both spot and early morning positive sputum report were 902, only spot positive were 24 in number and only early morning positive were 28 in number [Table 3 and 4]. Spot sample when compared with spot plus early morning sample gave sensitivity of 96.98%, specificity 99.47%, positive predictive value 97.40%, negative predictive value 99.38 %. While early morning sample when compared with spot plus early morning sample gave sensitivity of 97.40%, specificity 99.38%, positive predictive value 96.98% negative predictive value 99.47 %. There is no significant difference in sputum positivity as detected using spot or morning sample alone for sample collected in 2012 and 2013 (P value 0.191 and 0.939 respectively). [Table 5 and 6]
DISCUSSION
In 1993, the WHO declared tuberculosis to be a global health emergency.8 The most common and widely used diagnostic method for diagnosis is sputum smear microscopy in which bacteria are observed in sputum sample under microscope1,9 . The current RNTCP guideline recommends two sputum examinations, one is spot and other is early morning sputum5 . It requires two days visit to health facility, thereby increasing chances of patient drop out. If sputum examination is done on the first day of visit then patient will save the cost of travelling and daily wages, reduce chances of transmission of tuberculosis while travelling and reduce the number of visit and thereby the patient dropout rate.
Statistical analysis for association between positivity of samples in present study showed that spot sample is as good as early morning sample for diagnosis of sputum positivity and difference between two samples is by chance. Few studies by T. Jaya Chandra, Dr. Shafiyabi S. et al and Yassin MA et al showed that one day method test approach was equally effective as two days method in identifying cases10, 11, 12 . However, cross-sectional study conducted by Priyakanta et. al. showed that same day sputum microscopy method missed 17% of smear positive cases in their study13 . A pilot study conducted by Myneedu VP et.al. concluded that same day sputum microscopy does not seem to be a promising step towards improving quality of sputum14 . If result of one sputum turns out to be positive, the second sputum sample examination may not be much helpful without compromising quality of sputum. Examination of first day two sputum specimens taken one hour apart is much more convenient to the patient and as well as for operational purpose in RNTCP. Diagnosis of smear negative pulmonary tuberculosis can be increased by doing Chest X- ray examination on same day.
CONCLUSION
From this study, it may conclude that spot sample is as good as early morning sample sputum sample for diagnosis of sputum positive pulmonary tuberculosis. Same day two spot specimen examination one hour apart will be helpful for early diagnosis and reduce patients’ dropout rate for follow up visit on next day. Because of patient friendly strategy, diagnosis of smear negative Pulmonary Tuberculosis cases may increase indirectly and it will possible to implement it on operational grounds under programmatic condition. However, multi-centric large scale studies are required to effectively implement this strategy under RNTCP. This provides furtherscope for studies for diagnosis based on two spot and one overnight or same day versus routine protocol for sputum examination.
ACKNOWLEDGEMENT
We would like to express our gratitude to Dean and Medical Superintendent of Medical College Vadodara for their constant encouragement and guidance for research publication. We authors are very much thankful to District TB officer and all staff members at Designated Microscopy center at Medical College, Vadodara for their constant and valuable support. Our heartfelt thanks especially to laboratory technicians of DMC who gives their valuable guidance in collecting data for study. The authors would like to acknowledge all authors whose cited articles guided us in conducting this retrospective study and provided very much insight in preparing this research article. The authors are very much thankful to editors and publishers of books and of journal from where we got literature for making this article successful. Last but not least we are very much thankful to our residents doctors for their support and enthusiasm.
Abbreviations: DMC : Designated Microscopy Center TB : Tuberculosis AFB : Acid Fast Bacilli Z - N Stain : Zeil - Nelson Stain RNTCP : Revised National Tuberculosis Control Programme WHO : World Health Organization
References:
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