External Quality Control for Dried Blood Spot-Based C-Reactive Protein Assay: Experience from the Indonesia Family Life Survey and the Longitudinal Aging Study in India

Abstract

Measurement of C-reactive protein (CRP), a marker of inflammation, in dried blood spots has been increasingly incorporated into community-based social surveys internationally. Although the dried blood spot-based CRP assay protocol has been validated in the United States, it remains unclear whether laboratories in other less-developed countries can generate CRP results of similar quality. We therefore conducted external quality monitoring for dried blood spot-based CRP measurement for the Indonesia Family Life Survey and the Longitudinal Aging Study in India. Our results show that dried blood spot-based CRP results in these two countries have excellent and consistent correlations with serum-based values and dried blood spot-based results from the reference laboratory in the United States. Even though the results from duplicate samples may have fluctuations in absolute values over time, the relative order of C-reactive protein levels remains similar, and the estimates are reasonably precise for population-based studies that investigate the association between socioeconomic factors and health.

Additional information

Funding

Funding for the LASI pilot study was provided by National Institute on Aging (NIA) Grant 1R21 AG034443. Funding for the IFLS4 was provided by NIA Grant 1R01 AG026676; National Institute for Child Health and Human Development (NICHD) Grant 1R01 HD050764; and grants from the World Bank, Indonesia Office, and the Australian Aid Agency (AUSAID). Funding for the USC/UCLA Center on Biodemography and Population Health (CBPH) was provided by NIA Grant P30 AG017265.