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Biomedical subjects

S Radhakrishna

Publications and source records attributed to S Radhakrishna.

At least 19 recordsLinked to original sources
PubMed2006

Active community surveillance of the impact of different tuberculosis control measures, Tiruvallur, South India, 1968-2001.

BACKGROUND: Tuberculosis is curable, but community surveys documenting epidemiological impact of the WHO-recommended DOTS strategy on tuberculosis prevalence have not been published. We used active community surveillance to compare the impact of DOTS with earlier programmes. METHODS: We conducted tuberculosis disease surveys using random cluster sampling of a rural population in South India approximately every 2.5 years from 1968 to 1986, using radiography as a screening tool for sputum examination. In 1999, DOTS was implemented in the area. Prevalence surveys using radiography and symptom screening were conducted at the start of DOTS implementation and after 2.5 years. RESULTS: From 1968 to 1999, culture-positive and smear-positive tuberculosis declined by 2.3 and 2.5% per annum compared with 11.9 and 5.6% after DOTS implementation. The 2.5 year period of DOTS implementation accounted for one-fourth of the decline in prevalence of culture-positive tuberculosis over 33 years. Multivariate analysis showed that prevalence of culture-positive tuberculosis decreased substantially (10.0% per annum, 95% CI: 2.8-16.6%) owing to DOTS after only slight declines related to temporal trends (2.1% annual decline, 95% CI: 1.1-3.2%) and short-course chemotherapy (1.5% annual decline, 95% CI: -9.7% to 11.5%). Under DOTS, the proportion of total cases identified through clinical care increased from 81 to 92%. CONCLUSIONS: Following DOTS implementation, prevalence of culture-positive tuberculosis decreased rapidly following a gradual decline for the previous 30 years. In the absence of a large HIV epidemic and with relatively low levels of rifampicin resistance, DOTS was associated with rapid reduction of tuberculosis prevalence.

Adolescent↗
PubMed2005

Value of dual testing for identifying tuberculous infection.

SETTING: A rural community in Chingleput district in Tamil Nadu state in south India. OBJECTIVE: To determine the value of dual testing with PPD-S and PPD-B for identifying subjects with a tuberculous infection. DESIGN: About 240,000 subjects in rural south India, all of whom were tested initially with PPD-S and PPD-B, were followed up for 15 years, mainly by total population survey once in every 212 years. The incidence of culture-positive tuberculosis was estimated using life-table technique. RESULTS: Among 17,530 subjects with an intermediate reaction (8-11 mm) to PPD-S at intake, 285 with an induration to PPD-S exceeding the induration to PPD-B by at least 2mm, had a significantly higher incidence of culture-positive tuberculosis than the remaining (154 and 93 per 100,000), and similarly 481 who had an induration of <10mm to PPD-B compared to those with >or=10 mm (131 and 93 per 100,000). These subjects may be regarded as having a tuberculous infection. Infection with non-tuberculous mycobacteria conferred protection of about 30% against the development of tuberculosis over a 15-year period. CONCLUSION: In subjects with an intermediate reaction (8-11 mm) to PPD-S, dual testing with PPD-B enabled identification of those with a tuberculous infection. Most of the reactions were due to non-tuberculous mycobacteria.

Adolescent↗
PubMed2003

Association of initial tuberculin sensitivity, age and sex with the incidence of tuberculosis in south India: a 15-year follow-up.

OBJECTIVE: To determine the association of initial tuberculin sensitivity, age and sex with the development of tuberculosis. METHODS: A 15-year follow-up of 280000 subjects in south India, where new cases of tuberculosis were detected mainly by periodic population surveys. Life-table technique was employed to estimate tuberculosis incidence and disease risk in survivors. The independent effect of tuberculin sensitivity, sex and age at intake was determined using Cox's proportional hazard model. RESULTS: Taking subjects with reaction size 0-7 mm to 3 IU PPD-S as reference group, the adjusted relative risk (RR) for developing culture-positive tuberculosis was 1.1, 1.9, 2.9, 3.6 and 3.3 for those with indurations of 8-11, 12-15, 16-19, 20-24 and > or = 25 mm (P < 0.01). Considering subjects aged 0-4 years as reference group, the adjusted RR for the other groups increased from 1.7 to 10.8 (P < 0.01). Males had a substantially higher incidence (adjusted RR 3.0, P < 0.001). The risk of culture-positive tuberculosis over 15 years in survivors was 3.3% (5.0% in males and 1.6% in females), and increased substantially with tuberculin sensitivity at intake. In those with > or = 12 mm at intake, the approximate lifetime risk was 6.1% (8.6% in males and 3.1% in females). CONCLUSION: The incidence of tuberculosis increased steadily with tuberculin sensitivity to PPD-S and age at intake. Males had a significantly higher risk than females in every PPD-S group and the overall risk was three-fold higher.

Adolescent↗
PubMed2003

A baseline survey of the prevalence of tuberculosis in a community in south India at the commencement of a DOTS programme.

OBJECTIVE: To determine the baseline prevalence of culture-positive and smear-positive tuberculosis and the annual risk of tuberculous infection (ARTI) in a community in south India where DOTS is being implemented. METHODS: Using cluster sampling, 50 rural panchayats (villages) and three urban units in Tiruvallur district were selected randomly. All adults aged > or = 15 years underwent symptom and radiographic examination, and those with abnormal shadows and/or chest symptoms had sputum smear and culture examination. In another cluster sample of 73 villages and three urban units, all children aged < 10 years were tuberculin tested. RESULTS: The prevalence of culture-positive and smear-positive tuberculosis was respectively 605 and 323/100,000. Both increased appreciably with age, and were substantially higher in males than in females at all ages; the overall male:female ratio was 5.5 for culture-positive and 6.5 for smear-positive tuberculosis. The ARTI in children aged under 10 years was 1.6%, and was unaffected by sex. Over three decades there was an overall decline of 1.8% per annum in the prevalence of culture-positive and 2.1% for smear-positive tuberculosis. CONCLUSION: Tuberculosis is a major problem in this rural community in south India, with a prevalence of 605/100,000 for culture-positive tuberculosis and 323/100,000 for smear-positive tuberculosis.

Adolescent↗
PubMed2001

Trends in the prevalence and incidence of tuberculosis in south India.

OBJECTIVE: To study trends in the prevalence and incidence of tuberculosis in south India. METHODS: In 1968-1970, about 100,000 subjects were surveyed for tuberculosis and followed thereafter for 15 years, mainly by repeat survey once every 2.5 years. New entrants were inducted at every repeat survey. Radiographic examination of subjects aged 5 years or more and sputum smear and culture examinations of those with an abnormal shadow were undertaken; tuberculin tests were done initially on all, and at 4, 10 and 15 years in selected samples of those aged 1-9 years. RESULTS: The prevalence of culture-positive tuberculosis decreased by 1.4% per annum to 694/100,000, while that of smear-positive tuberculosis showed no significant decrease from 457/100,000. The annual incidence of culture-positive tuberculosis decreased by 4.3%/annum to 189/100,000 and that of smear-positive tuberculosis decreased by 2.3%/annum to 113/100,000. Decreases in incidence occurred exclusively in those with abnormal radiographic findings suggestive of tuberculosis at the start of the period. The annual risk of tuberculosis infection (ARTI) was initially 2%, and showed no sign of decline over the period. CONCLUSION: The prevalence of tuberculosis and ARTI showed little or no decrease over the 15-year period. A significant decrease in incidence occurred, but exclusively in those with abnormal radiograph suggestive of tuberculosis at the start of the period.

Adolescent↗
PubMed2001

Chitra heart valve: results of a multicenter clinical study.

BACKGROUND AND AIM OF THE STUDY: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultra-high molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder. METHODS: Between December 1990 and January 1995, 306 patients underwent isolated aortic (AVR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr). RESULTS: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven years were 82.4+/-4.0% for AVR and 65.2+/-5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9+/-1.1% and 94.1+/-1.9%, and 92.3+/-2.8% and 82.1+/-5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5+/-4.1% after AVR, and 64.2+/-5.1% after MVR. CONCLUSION: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients.

Adolescent↗
PubMed2000

Tuberculosis in the urban poor settlements in the Philippines.

SETTING: Urban poor settlements in the Philippines. OBJECTIVE: To determine the magnitude of the tuberculosis problem in urban poor settlements in comparison with urban areas studied in the Nationwide Tuberculosis Prevalence Survey. STUDY DESIGN AND METHOD: A multistage cluster survey of BCG scar, tuberculin test, chest radiography and sputum examination for bacillary disease, in urban poor areas. RESULTS: The prevalences of culture-positive and smear-positive tuberculosis were 17.5 +/- 2.3 (95% CI 13.3-22.4) and 7.9 +/- 2.3 per thousand (95% CI 2.611.5), respectively. Extrapolated to the total population, the rates in the urban poor settlements were 12.4 +/- 1.7 (95% CI 9.6-16.2) and 5.6 +/- 1.6 per thousand population (95% CI 1.3-8.3), respectively. The prevalence of active pulmonary tuberculosis in subjects aged 10 years or more was 66 +/- 5.6/1000 (95% CI 55-77). The BCG vaccination rate was 72%. The overall prevalence of tuberculosis infection was 66%, and 39% in those aged 5-9 years, corresponding to an annual risk of infection (ARI) of 6.5%. CONCLUSION: The problem of tuberculosis was substantial in the urban poor settlements, and was appreciably worse than that in the general urban population.

Adolescent↗
PubMed2000

Direct drug susceptibility test for tubercle bacilli by the sputum swab culture method.

OBJECTIVE: To develop a simple, inexpensive method for testing direct drug susceptibility of tubercle bacilli to isoniazid (INH) and streptomycin (SM) which can be adopted for use even in remote parts of the world. DESIGN: Using 239 smear-positive sputum specimens obtained from an equal number of patients, a comparison was made between the direct swab susceptibility test and the standard indirect method for INH and SM using Löwenstein-Jensen (L-J) medium. RESULTS: There was 95% agreement of results for INH by 6 weeks and 90% for SM by 8 weeks; 96% of INH-resistant cultures could be detected in 5 weeks and 91% of SM-resistant cultures by 8 weeks. The discrepancies in the two tests were virtually symmetrically distributed at 6 and 8 weeks. The speed and efficiency of detection of resistance by the swab method was also assessed in relation to the standard indirect method. For INH, 96% of the cultures were detected by the fifth week, while 66% were detected as early as 2 weeks and 93% by 4 weeks. With SM, 84% were detected by 4 weeks, 89% by 5 weeks and 91% by 8 weeks. CONCLUSION: This study has indicated the usefulness of the swab method for testing the drug susceptibility of tubercle bacilli. As this method is simple and easy, and does not even require a centrifuge, it has the potential of application even in the remote parts of the world. The material used, Cetavlon (Cetrimide), is inexpensive and easily water soluble, and more importantly, aqueous solutions are self-sterilizing. It should be stressed, however, that the results obtained with this test take the same time as conventional methods, and it can therefore not be considered as a rapid test.

Antibiotics, Antitubercular↗
PubMed2000

BCG coverage and the annual risk of tuberculosis infection over a 14-year period in the Philippines assessed from the Nationwide Prevalence Surveys.

SETTING: A prevalence survey of tuberculosis (TB) infection was undertaken in the Philippines, a developing country in the Western Pacific region. OBJECTIVE: To determine the bacille Calmette Guerin (BCG) vaccination rate, the prevalence of TB infection and the annual risk of TB infection (ARTI). METHODS: A nationwide stratified multi-stage cluster survey of 21,960 individuals. BCG scar verification and tuberculin test were performed on those aged > or =2 months. The ARTI was calculated using the prevalence rates of TB infection in children aged 5-9 years. RESULTS: BCG scars were noted in 66% of the study population. The prevalence of TB infection was 63.4% among unvaccinated individuals. The prevalence rate was higher in males in both urban and rural areas. With both sexes combined, urban and rural communities had similar prevalence rates. In children aged 5-9 years, the prevalence rate was 16.1% (males 17.4%, females 14.9%), corresponding to an ARTI of 2.3% (males 2.5%, females 2.1%). CONCLUSION: BCG coverage increased substantially between 1981-1983 and 1997. The ARTI, however, was virtually unchanged, indicating that morbidity due to TB continued to be high.

Adolescent↗
PubMed2000

Bacillary disease and health seeking behavior among Filipinos with symptoms of tuberculosis: implications for control.

SETTING: Urban and rural communities and urban poor settlements in the Philippines. OBJECTIVE: To determine bacillary disease and action taking among individuals with symptoms of tuberculosis (TB), and to analyze their implications for TB control. STUDY DESIGN AND METHOD: Subjects aged 20 years and older were interviewed in the 1997 nationwide stratified multi-cluster survey. Sputum acid-fast smears and cultures were done in subjects with abnormal screening chest radiographs. RESULTS: Individuals with TB symptoms comprised 18.1% of the population studied. The prevalence of bacillary disease was 39/1000 in symptomatic subjects compared to 13/1000 in asymptomatic subjects. Symptom screening had a 14.3% positive predictive value and a 91.4% negative predictive value for bacillary disease. Significantly more symptomatic than asymptomatic subjects attended chest radiographic screening during the survey. However, in response to their symptoms, the majority (43.0%) took no action or self medicated (31.6%), while 11.8% consulted a private practitioner, 7.5% a public health center, 4.4% a hospital, and 1.7% a traditional healer. CONCLUSION: Sputum smear examination after symptom screening was acceptable for case finding. The health seeking behavior of subjects with TB symptoms was inappropriate. A health education program and public-private collaboration in directly observed therapy, short course (DOTS) are essential for TB control in the Philippines.

Adult↗
PubMed1999

Syringe labels in anaesthetic induction rooms.

A survey of 35 hospitals in the United Kingdom has uncovered a wide variety of syringe drug labels. Use of different systems in different hospitals may result in wrong drug administrations, particularly when trainees move from one hospital to another. There is an urgent need to standardise the colour coding of syringe labels in the United Kingdom. Such standards are already in place in Australia, New Zealand and in the United States of America. This survey of syringe drug labels highlights the existing risks and recommendations for change are made.

Anesthesiology↗