With respect to Hypotheses 2 and 3, the studies we reviewed demonstrate that:
1. Some large outbreaks of respiratory and ILI can be detected from aggregate analysis of ICD codes. Small outbreaks of gastrointestinal illness generally cannot. There were no studies of large outbreaks of gastrointestinal illness (Hypothesis 2).
2. Research to date is suggestive but not conclusive that outbreaks of influenza can be detected earlier than current surveillance methods (Hypothesis 3).
3. The methodological weaknesses of studies included:
a. Not measuring all three characteristics of outbreak-detection performance (false alarm rate, sensitivity, and timeliness).
14 They used the same same Respiratory ICD code set as Espino and colleagues (Espino and Wagner, 2001).
15 They do not report the correlation measurement, but in one figure in the paper, the correlation of the Respiratory code set appears close to 1.0 at a time lag of two weeks.
b. Not reporting either the correlation or the time lag at which correlation was maximal.
c. Measuring correlation at too few time lags (sometimes at just one or two values).
d. Not reporting sampling completeness.
4. In general, the number of published studies is small,perhaps due to the fact that ICD monitoring systems are relatively recent. We expect more studies to be published in the near future.
Was this article helpful?