Volume 21, Number 12—December 2015
Dispatch
Kinetics of Serologic Responses to MERS Coronavirus Infection in Humans, South Korea
Table 2
Testing potential difference in rates of change in antibody titers over day of illness during the exponential phase of the antibody response, accounting for sequential measurements taken at different days of illness and adjusted for severity*
Clinical factors | Difference in rates of change in log antibody titers |
||||
---|---|---|---|---|---|
PRNT50 titer | p value | S1-ELISA OD ratio | p value | ||
Severe disease | 0.09 | 0.01 | 0.08 | 0.07 | |
Male sex† | 0.07 | 0.05 | 0.14 | 0.01 | |
Age >60 y† | 0.05 | 0.22 | −0.03 | 0.65 | |
Incubation period, d† | 0.01 | 0.16 | 0.02 | 0.004 | |
Use of corticosteroid† | 0.06 | 0.37 | −0.04 | 0.58 | |
Use of antiviral drugs† | 0.06 | 0.10 | 0.05 | 0.35 | |
Concomitant conditions† | 0.06 | 0.06 | 0.07 | 0.16 |
*Differences in rates of change and p values were estimated by using linear mixed models; positive value indicates a faster increase in antibody titer. Given that the antibody titers exhibited an S-shaped pattern, the analysis was restricted to data for log-phase antibody responses by manually removing data from the inductive/steady-state phase. Increases in antibody titers during the log phase were compared by different factors, adjusted for disease severity, by using a linear mixed model to account for repeated measurements, assuming a linear increasing trend by days since illness onset. PRNT50 titers were first log-transformed (with base 10). OD, optical density; PRNT50, 50% endpoint plaque reduction neutralization test.
†Effects were adjusted for severity.
1These authors contributed equally to this article.