While claims data provide large samples at relatively low costs, key variables may be missing in the databases to fully assess the healthcare resource utilization (HCRU) and costs associated with particular conditions. The absence of these key variables may also introduce bias into the estimates of HCRU and cost particularly when regression based approaches are used. Chart abstractions based on reviews of medical records often overcome many of these limitations and provide a standard of internal validity by which to evaluate the analyses based on claims data. This study presents estimates of HCRU based on abstractions of information from physician notes and laboratory tests in a population based study of care associated with herpes zoster and its complications including postherpetic neuralgia.