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Sub-Saharan Africa is the region most heavily affected by the HIV/AIDS epidemic. HIV increases the risk of developing cancer but the ascertainment of cancers in patients attending antiretroviral therapy (ART) treatment programs might be incomplete. To estimate the under-ascertainment of cancer we compared incidence rates of AIDS-defining cancers in South African HIV cohorts with and without cancer case ascertainment through record linkage with the National Cancer Registry.
We used the data of adult (≥16 years) HIV-positive persons receiving care between 2004 and 2011 at one of four ART programs in South Africa. These programs collaborate with the International Epidemiologic Databases to Evaluate AIDS Southern Africa (www.iedea-sa.org) and collected data for AIDS-defining cancers but not for other cancers. To improve cancer ascertainment we probabilistically linked patient records (using first name, surname, age, and gender) from two HIV cohorts with the cancer records of the South African National Cancer Registry. We calculated incidence rates per 100,000 person-years after starting ART for the AIDS-defining cancers, i.e. Kaposi sarcoma (KS), invasive cervical cancer (ICC) and non-Hodgkin lymphoma (NHL). We compared incidence rates before and after inclusion of record linkage identified cancer cases using the attributable fraction of cancers identified with 95% confidence intervals (CI).
A total of 49,207 adults starting ART in South Africa were included. 65% of patients were female, median age at starting ART was 35 years (interquartile range 30-41 years). We identified a total of 471 incident cancer cases. With record linkage the incidence increased from 81 to 292 for KS, from 1 to 119 for NHL and 12 to 497 for ICC per 100,000 person-years. The attributable fraction of cancers identified was 72% (95% CI 63-79%) for KS, 98% (95% CI 94-99%) for NHL and 98% (95% CI 95-99%) for ICC.
Ascertainment of cancer in HIV program data in African settings is incomplete. This case study has shown that probabilistic record linkage to cancer registries is both feasible and essential for cancer ascertainment in HIV cohorts in South Africa.
Cost-burden analyses usually lack a wider societal perspective. Through the creation of a robust resource use measure (RUM), data gaps on societal costs will be addressed, allowing more accurate estimates of the cost burden of asthma in the UK.
A systematic review, applying an established checklist and data extraction tool, will identify and evaluate those existing methods and measures of generating resource use data. These data, incorporated with focus group data, will inform the design of a new RUM. To be distributed to 2000 participants, randomly selected from GP practices (Swansea & Edinburgh), the Swansea data will be linked and validated with their record held in SAIL (Secure Anonymised Information Linkage). A nested cost burden analysis will be applied, generating an estimate of relevant societal costs.
A preliminary search of the `PubMED' database generated 181 papers that met the inclusion criteria. Initial analysis shows that a societal perspective is usually lacking from RUMs. A critical appraisal of these measures has identified significant variance in both the quality and content of the questionnaires. Focus groups highlighted a number of cost elements that are not, as yet, discussed in the literature.
Societal cost factors are not adequately captured within existing tools, our findings will inform the development of a new RUM which will be piloted and validated according to best practice guidelines. Capturing the societal costs of asthma will allow more accurate estimates of the total costs of asthma in the UK.
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