Background
Little is known about the medical care resources devoted to diagnosing and treating cancer-related symptoms prior to a definitive cancer diagnosis. Previous research using SEER-Medicare data to measure incremental costs and utilization associated with cancer started with the date of diagnosis. We hypothesized that health care use increases prior to diagnosis of a new primary cancer.
Methods
We used a longitudinal case-control design to estimate incremental medical care utilization rates. Cases were 121,293 persons enrolled between January, 2000 and December, 2008 with one or more primary cancers. We selected 522,839 controls randomly from among all health plan members who had no tumor registry evidence of cancer prior to January, 2009, and we frequency matched controls to cancer cases on a five-to-one ratio by age group, gender, and having health plan eligibility in the year of diagnosis of the index cancer case. Utilization data were extracted for all cases and controls for the period 2000-2008 from standardized distributed data warehouses. To determine when and the extent to which patterns of medical care use change preceding a cancer diagnosis, we compute hospitalization rates, hospital days, emergency department visits, same-day surgical procedures, ambulatory medical office visits, imaging procedures, laboratory tests, and ambulatory prescription dispensings per 1,000 persons per month within integrated delivery systems.
Results
One- to three-fold increases in monthly utilization rates were observed during the three to five months prior to a cancer diagnosis, compared to matched non-cancer control groups. This pattern was consistent for both aged and non-aged cancer patients. Aged cancer patients had higher utilization rates than non-aged cancer patients throughout the year prior to a cancer diagnosis.
Conclusion
The pre-diagnosis phase is a resource-intensive component of cancer care episodes and should be included in cost of cancer estimates. More research is needed to determine whether reliable prognostic markers can be identified as the start of a cancer episode prior to a pathology-based diagnosis.