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BMC Med Res Methodol. 2012; 12: 110.
Published online 2012 July 28. doi:  10.1186/1471-2288-12-110
PMCID: PMC3475121

Using two on-going HIV studies to obtain clinical data from before, during and after pregnancy for HIV-positive women

Susie E Huntington,corresponding author1,2 Loveleen K Bansi,1 Claire Thorne,2 Jane Anderson,3 Marie-Louise Newell,2,4 Graham P Taylor,5 Deenan Pillay,1,6 Teresa Hill,1 Pat A Tookey,2 and Caroline A Sabin1, on behalf of the UK Collaborative HIV Cohort (UK CHIC) Study and the National Study of HIV in Pregnancy and Childhood (NSHPC)

Abstract

Background

The UK Collaborative HIV Cohort (UK CHIC) is an observational study that collates data on HIV-positive adults accessing HIV clinical care at (currently) 13 large clinics in the UK but does not collect pregnancy specific data. The National Study of HIV in Pregnancy and Childhood (NSHPC) collates data on HIV-positive women receiving antenatal care from every maternity unit in the UK and Ireland. Both studies collate pseudonymised data and neither dataset contains unique patient identifiers. A methodology was developed to find and match records for women reported to both studies thereby obtaining clinical and treatment data on pregnant HIV-positive women not available from either dataset alone.

Results

Women in UK CHIC receiving HIV-clinical care in 1996–2009, were found in the NSHPC dataset by initially ‘linking’ records with identical date-of-birth, linked records were then accepted as a genuine ‘match’, if they had further matching fields including CD4 test date. In total, 2063 women were found in both datasets, representing 23.1% of HIV-positive women with a pregnancy in the UK (n = 8932). Clinical data was available in UK CHIC following most pregnancies (92.0%, 2471/2685 pregnancies starting before 2009). There was bias towards matching women with repeat pregnancies (35.9% (741/2063) of women found in both datasets had a repeat pregnancy compared to 21.9% (1502/6869) of women in NSHPC only) and matching women HIV diagnosed before their first reported pregnancy (54.8% (1131/2063) compared to 47.7% (3278/6869), respectively).

Conclusions

Through the use of demographic data and clinical dates, records from two independent studies were successfully matched, providing data not available from either study alone.

Keywords: Data linkage, HIV, Pregnant women, Antiretroviral therapy, Cohort analysis, United Kingdom

Articles from BMC Medical Research Methodology are provided here courtesy of BioMed Central