S Hayward, AC;
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Mobile targeted digital chest radiography in the control of tuberculosis among hard to reach groups.
Health Protection Agency/ Department of Health: London, UK.
Executive summary This report presents an epidemiological and economic assessment of targeted digital mobile chest radiography to inform key policy decisions on tuberculosis (TB) control in London. Main Findings · A total of 23,881 chest x-rays were made from 20,357 individuals over twenty one months. From this activity 222 persons were referred with abnormal chest x-rays suggestive of active TB of which 154 (69%) were seen by TB services for further diagnostic tests and 43 commenced on treatment for active disease (89% culture confirmed). · Very high rates (per 100,000 screened) of undetected TB were found among problem drug users (717), homeless people (338) and prisoners (200). No TB cases were detected through screening community groups. · On multivariate analysis, passively detected cases were found to have almost three times the delay to diagnosis than cases detected by the Mobile X-ray Unit (MXU). Passively identified cases were also three times more likely to have advanced infectious (sputum smear positive) TB. · Mathematical modelling suggests that the MXU can interrupt transmission and prevent future cases in hard to reach groups. It is estimated that the intervention prevented 11 cases of active TB and 60 infections in the first year with projected estimates of active cases prevented increasing to about 87 active cases and 389 infections prevented per year by 2013 with current activity. · Doubling of current capacity (two MXU’s) and increased follow up of cases (from 69% to 90%) suggests that 24 active TB cases and 136 infections can be prevented in the first year increasing to over 122 active cases and 602 infections prevented per year by 2013. · With current activity, the MXU costs £2,180 on average to prevent one case of active TB among the target populations (ICER = £2,180) assuming TB treatment costs of £5000 per case. The estimated cost per QALY is £3,206 (min. £1,397 max. £15,572). If average treatment costs for hard to reach groups are assumed to be £10,000 per case then the MXU saves £1,912 per case prevented (ICER = -£1,912). As this scenario is cost saving, cost per QALY estimates are not appropriate. 4 · Uptake of the intervention in different settings varied from 30% to 90% and was primarily determined by the ability of local staff to engage pro-actively with clients, and providing small incentives and clear information. Anonymous questionnaires and one-to-one interviews undertaken by trained peers suggest the intervention is highly acceptable to the target populations. Overall accessibility of the intervention is limited by the capacity of one unit to provide a pan-London service as only 70 of over 400 eligible venues providing residential or day services to homeless people or drug and alcohol misusers have been reached in the 21 months evaluated. Conclusion: Active case finding with the MXU is clinically and cost effective, acceptable and accessible to the populations targeted and those who work with them. Other benefits include prevention of onward transmission, raising awareness and re-engaging cases who are lost to follow up with TB treatment services . There is a need to improve targeting and uptake of the intervention, strengthen outreach capacity across the capital and fast-track referred cases through diagnosis and onto treatment.
|Title:||Mobile targeted digital chest radiography in the control of tuberculosis among hard to reach groups.|
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