272710 Missing data on melanoma tumor thickness in the United States and its consequences

Monday, October 29, 2012

Waqas Shaikh, BS , Department of Epidemiology and Biostatistics, SUNY Downstate Medical Center School of Public Health, Brooklyn, NY
Martin Weinstock, MD, PhD , Brown University, VA Medical Center, Providence, RI
Allan Halpern, MD, MSc , Dermatology Service, Memorial Sloan-Kettering Cancer Center, New York, NY
Susan Oliveria, PhD , Dermatology Service, Memorial Sloan-Kettering Cancer Center, New York, NY
Alan Geller, MPH, RN , Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, MA
Stephen Dusza, DrPH , Dermatology Service, Memorial Sloan-Kettering Cancer Center, New York, NY
In the United States, the Surveillance, Epidemiology, and End Results (SEER) Program is the authoritative source for population-based data on melanoma. However, missing data on tumor thickness may lead to biased analyses. We sought to characterize the association between invasive melanomas with unknown thickness and melanoma survival, and employ techniques to overcome the limitations of missing data on tumor thickness. We conducted a retrospective cohort analysis of invasive melanomas in the SEER database from 1989 to 2008. Of 182,184 cases, 24,329 (13%) had unknown thickness. From 1989-1993 to 2004-2008, the proportion of unknown thickness cases decreased from 22% to 9% (Ptrend < 0.001). Unknown thickness cases had a significantly increased risk of death due to melanoma (hazard ratio [HR] 3.09, 95% confidence interval [CI]: 2.99, 3.19) than known thickness cases with an increasing trend over time (Ptrend < 0.001). In multivariate analysis, unknown thickness was found to be independently associated with poorer prognostic factors and lack of cancer-directed surgical treatment. Melanoma survival of cases with unknown thickness appeared most similar to 2.01-4.00 mm thickness cases. Multiple imputation demonstrated that imputed tumor thickness was significantly associated with melanoma survival (HR 1.21, 95% CI: 1.20, 1.22) and Clark level (odds ratio [OR] 1.98, 95% CI: 1.94, 2.02). Exclusion of missing data on melanoma thickness from SEER introduces a selection bias that leads to an underestimation in the prevalence of fatal and likely thicker melanomas. Multiple imputation appears to be an effective tool to predict missing tumor thickness data.

Learning Areas:

Learning Objectives:
Describe the difference in melanoma survival between melanoma cases with known tumor thickness and unknown tumor thickness Discuss whether multiple imputation can overcome limitations of missing data on melanoma tumor thickness

Keywords: Cancer, Epidemiology

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am an MD/MPH candidate at SUNY Downstate Medical Center. I completed a year long dermatoepidemiology research fellowship at Brown University on skin cancer, melanoma, epidemiology and public health. I have published one paper and several abstracts on melanoma epidemiology. Furthermore, my co-authors are recognized experts in the field of melanoma epidemiology.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

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