Photo by Todd McNaught
A simple questionnaire customized by Clinical Research Division doctors can help clinicians better predict patient survival and likely complications following a blood stem-cell transplant.
The tool, called the hematopoietic cell transplantation-specific-comorbidity index (HCT-CI), was validated in a yearlong retrospective analysis of data from 1,055 Hutchinson Center patients. The HCT-CI captured 63 percent of coexisting health issues possibly affecting patient outcome compared to only 12 percent with a long-used earlier test. Study results were published June 30 in the online edition of the journal Blood.
"This index is important because it allows clinicians to determine which patients can receive high-dose conditioning regimens without undue risk, which ones should receive mini-transplants and which ones shouldn't be transplanted at all," said Dr. Rainer Storb, head of the Center's Transplantation Biology Program and a co-author on the paper.
In 2003, Center doctors began using a scale called the Charlson Comorbidity Index (CCI) to evaluate comorbidities — chronic health issues besides the primary disease — but the nearly 20-year-old CCI had shortcomings. While a poor CCI score was highly predictive of death from causes other than cancer relapse, the test was not specifically designed for cancer patients. It included conditions not applicable to a screened blood-cancer trial population, while ignoring other important values like diagnostic lab tests and infections. Hutchinson Center researchers found the CCI captured important comorbidities in only 12 percent of the Center's transplant patients with high-dose conditioning (chemotherapy and/or radiation before transplantation).
"We figured that we could do a better job if we could modify the CCI a little bit," said lead author Dr. Mohamed Sorror, a postdoctoral fellow working with Storb. "We put laboratory and organ-function test values and additional comorbidities into a new model that generates scores that fit our patients and their risks."
Dr. Barry Storer, director of the Clinical Statistics Program, performed the statistical analysis to convert the new comorbidity definitions into scores to help predict survival.
Evaluating comorbidities has become increasingly important since non-myeloablative transplants (mini-transplants) were developed at the Center in 1997. These transplants use a minimal dose of radiation and a transfusion of donor cells to treat cancer. The less-intensive procedure allows treatment for older patients and others who may be medically unfit to withstand the rigors of a conventional stem-cell transplant.
By definition, the less-healthy mini-transplant patients have additional medical problems besides cancer. "We needed to find a simple way to evaluate these comorbidities," Sorror said.
Sorror and colleagues calculated the correlation between the HCT-CI scores and an accurate forecast of patient outcome. They found the new test was highly predictive.
Sorror says the index will help with clinical trials since many patients with comorbidities have traditionally been excluded from studies. With a defined score, researchers may be able to include more patients with additional health issues.
The test will also help with patient counseling in the clinic setting. "We'll be able to understand ahead of time what kind of risk a patient has when he has other conditions in addition to cancer and what kind of outcome we can expect," Sorror said. Additionally, the physicians hope to understand if there is a connection between cormorbidities before transplant and post-transplant complications like graft-vs.-host disease or infections. If so, treatment can be altered.
The test is being incorporated into all new clinical-trial protocols at the Seattle Cancer Care Alliance. Center researchers also plan to collaborate with other institutions to further validate the index with different patient populations and treatment regimens.