Racial Disparities after Heart Transplant: Evidence from IMAGE

Utility of gene expression profiling score variability to predict clinical events in heart transplant recipients

BACKGROUND

Gene expression profiling test scores have primarily been used to identify heart transplant recipients who have a low probability of rejection at the time of surveillance testing. We hypothesized that the variability of gene expression profiling test scores within a patient may predict risk of future events of allograft dysfunction or death.

METHOD

Patients from the IMAGE study with rejection surveillance gene expression profiling tests performed at 1- to 6-month intervals were selected for this cohort study. Gene expression profiling score variability was defined as the standard deviation of an individual's cumulative test scores. Gene expression profiling ordinal score (range, 0-39), threshold score (binary value=1 if ordinal score ≥ 34), and score variability were studied in multivariate Cox regression models to predict future clinical events.

RESULTS

Race, age at time of transplantation, and time posttransplantation were significantly associated with future events in the univariate analysis. In the multivariate analyses, gene expression profiling score variability, but not ordinal scores or scores over threshold, was independently associated with future clinical events. The regression coefficient P values were <0.001, 0.46, and 0.773, for gene expression profiling variability, ordinal, and threshold scores, respectively. The hazard ratio for a 1 unit increase in variability was 1.76 (95% CI, 1.4-2.3).

DISCUSSION

The variability of a heart recipient's gene expression profiling test scores over time may provide prognostic utility. This information is independent of the probability of acute cellular rejection at the time of testing that is rendered from a single ordinal gene-expression profiling test score.

Outcome following heart transplantation in New Zealand Maori

BACKGROUND

Disparities in health care access and outcomes between Maori (M) and Non-Maori (NM) New Zealanders have been reported but little is known about access to and outcomes following heart transplantation (HT).

METHODS

A retrospective analysis was performed of M and NM who underwent HT in New Zealand. Demographic, clinical and outcome data were collected.

RESULTS

Of 253 patients transplanted, 176 were European, 47 M (19%) and 30 of other ethnicities. M and NM groups were compared. Median age (both 46 years), gender (17% vs 21% female), waiting time (90 vs 76 days) and diagnosis (dilated cardiomyopathy - 62% vs 58%) were similar for both groups. M were heavier (81 vs 71 kg, p<0.0001) and more were blood group A (58% vs 39%). Five year survival was similar (79% vs 78%) but 10 year survival was significantly reduced in M (54% vs 67% p=0.02).

CONCLUSION

The proportion of Maori who have undergone heart transplantation in New Zealand compares favourably with their proportion in the New Zealand population. The reasons for the adverse diverging outcomes after five years require further investigation.