UPDATED: 4.27.14, 2215 EST
In my last series of posts, it became quickly apparent that MERS cases who have pre-existing conditions (or “comorbidities”, such as diabetes, heart disease, etc.) are more likely to die than those who are otherwise healthy. I wanted to take a closer look at this finding by conducting some risk analyses on the data I have available to me currently. I looked at three different time frames: from March 2012 (when MERS was first documented) to present; before 3/20/2014 (the onset of the current outbreak in the Middle East); and after 3/20/2014. This is what I found:
Overall, cases with comorbidities are +80% (p = .0001) more likely to die than those who are otherwise healthy.
Prior to the current outbreak, cases with comorbidities were +70% (p = .0016) more likely to die than otherwise healthy cases – about the same as what we saw above, if we consider the confidence interval.
…However, since the onset of the current outbreak, cases with comorbidities have been only +40% (p = .32) more likely to die than those without them! In fact, because the confidence interval for the relative risk calculation includes 1, it’s possible that – for this particular time period – there’s no relationship between comorbidity and mortality in MERS cases at all.
So, what does this all mean? The answer is two fold:
1. It’s true that individuals with pre-existing conditions are more likely to die from MERS than cases who are otherwise healthy.
2. However, this relationship has thus far been less pronounced – perhaps even non-existent – during the current surge of cases we’re seeing in the Middle East.
Why, you ask? Well, something’s definitely going on… But we won’t know for sure until we have mortality data on all cases that are currently still active. We’ll have hold on tight for now!
Note: Temporal data indicates date of onset, hospitalization, diagnosis, or public reporting.
Data Sources: KSA MoH & WHO