Validation of HIV-infected cohort identification using automated clinical data in the Department of Veterans Affairs

OBJECTIVES

The US Department of Veterans Affairs (VA) is the largest integrated health care provider for HIV-infected patients in the USA. VA data for HIV-specific clinical and quality improvement research are an important resource. We sought to determine the accuracy of using the VA Corporate Data Warehouse (CDW), a fully automated medical records database for all VA users nationally, to identify HIV-infected patients compared with a gold-standard VA HIV Clinical Case Registry (CCR).

METHODS

We assessed the test performance characteristics of each of our CDW criteria-based algorithms (presence of one, two or all of the following: diagnostic codes for HIV, positive HIV laboratory tests, and prescription for HIV medication) by calculating their sensitivity (proportion of HIV-positive patients in the CCR accurately detected as HIV-positive by the CDW algorithm) and positive predictive value (PPV; the proportion of patients identified by the CDW algorithm who were classified as HIV-positive from the CCR).

RESULTS

We found that using a CDW algorithm requiring two of three HIV diagnostic criteria yielded the highest sensitivity (95.2%) with very little trade-off in PPV (93.5%).

CONCLUSIONS

A two diagnostic criteria-based algorithm can be utilized to accurately identify HIV-infected cohorts seen in the nationwide VA health care system.

Comparison of some fiber optic configurations for measurement of luminescence and Raman scattering

Measurements are made for a number of dual fiber optic configurations to determine their relative sensitivity using bare fibers and graded-refractive-index lenses. An analysis of the background fiber emission for a typical silica-on-silica fiber (Diaguide, 200-microm core) is presented, and the origin (core or cladding) for several prominent Raman peaks is determined. Also, a forward-scattering fiber geometry is introduced, and the dependence of sensitivity on the type of optical termination and fiber separation is determined.

Ethidium analogues with improved resolution in the dye-buoyant density procedure

Analogues of ethidium chloride with large quaternary side chains have been synthesized and evaluated for improved resolution in the dye-buoyant density system for the separation of open and closed circular DNA. These compounds are similar to propidium which differs from ethidium by the replacement of an ethyl group by a methyldiethylaminopropyl group. The new analogues contain a triethylamino group attached to a methylene chain with 3, 5 or 7 carbons. With PM2 DNA the observed separation for propidium is 1.97 times that of ethidium and the new dyes show separations relative to ethidium of 2.27, 2.66 and 2.77. A correlation is established between the mass of the dye component and the observed separation which is retionalized on the basis of the four component thermodynamics describing this system.