MERS: Impact of comorbidity on mortality and disease severity

So, how do the presence of comorbidities among MERS cases impact mortality and disease severity?

I attempted to answer this question by creating two new charts. Each chart splits up the 408 cases reported thus far into four categories:
1. Cases with comorbidities, prior to the onset of the current outbreak we’re seeing in the Middle East (3/20/14)
2. Otherwise healthy cases, prior to 3/20/14
3. Cases with comorbidities, on and after 3/20/14
4. Otherwise healthy case, on and after 3/20/14

The first graph looks at comorbidity and mortality:
mers_comorbidity_mortality_4.27It’s immediately apparent that otherwise healthy individuals – both pre and post March 20th – experience far lower mortality rates than their comorbid counterparts. We see here again that fatality is much lower now than it was before the onset of the current outbreak – among healthy and comorbid cases alike. However, it also seems that comorbidity has been having LESS of an impact on mortality since March 20th than before; there’s less of a difference between fatality rates among comorbid cases (19%) and healthy ones (12%).

The second graph looks at comorbidity and disease severity:
mers_comorbidity_severity_4.27Perhaps unsurprisingly, the vast majority of asymptomatic MERS cases have occurred in otherwise healthy individuals. In fact, only 2 of the 69 total asymptomatic cases identified thus far have been individuals with documented pre-existing conditions. Overall though, it doesn’t look like the impact of comorbidity on disease severity has changed much pre and post March 20th.

In summary:
1. Comorbidities have historically resulted in greater fatality among MERS cases. (However, this appears to be less the case in the outbreak we’re witnessing right now. )
2. Asymptomatic MERS cases rarely ever occur in individuals with comorbidities; they are most often found in otherwise healthy individuals.

While data are incomplete and imperfect, it seems to me as though comorbidities have a significant impact on the severity of the disease, as well as likelihood of mortality. Why is this the case? Until we better understand how MERS-CoV is transmitted and how it operates within the human body, it’s hard to say. We’ll just have to wait and see what happens next!

Note: Temporal data indicates date of onset, hospitalization, diagnosis, or public reporting.
Data Sources: KSA MoH & WHO

4 thoughts on “MERS: Impact of comorbidity on mortality and disease severity

  1. Pingback: MERS: Updated Charts | Mens et Manus

  2. Pingback: MERS: Updated Charts | Mens et Manus

  3. Pingback: MERS in America: What you need to know | Mens et Manus

  4. Pingback: MERS: Updated Charts [& Improved Fatality Data] | Mens et Manus

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