We would like to reply to the letter from Chatni and Thankappan regarding our article titled “Factors Predictive of Survival in Advanced Laryngeal Cancer.”1 Two points were raised.
First, Chatni and Thankappan inquired about the confounding influence of nodal status: “In our view, if survival is being analyzed in patients with laryngeal cancer, the effect of the N category as a confounding factor must be a part of the analysis.” We evaluated the potential for confounding by adding nodal status (N0 vs N1, N2, or N3) into the multivariate proportional hazards regression model. The output suggests that nodal status did not have a confounding effect, as all hazard ratios remained essentially unchanged (Table). However, we did find that nodal status did have an independent effect on mortality, with hazard ratios of 1.37 for N1, 1.95 for N2, and 3.0 for N3 disease as compared with N0 disease.
Chen AY, Halpern MT. Lymph Node Status Cannot Be Ignored in Survival Analysis of Laryngeal Cancer—Reply. Arch Otolaryngol Head Neck Surg. 2008;134(7):786-787. doi:10.1001/archotol.134.7.786-b