Page 116 - Timeliness of Infectious Disease Notification & Response Systems - Corien Swaan

114 Chapter 5
Delaysshorter than0 orlonger than365 days were excluded, as a mistake in data entry was considered likely. In D3, weekend days were removed, as noti- fications are legally not obligatory in the weekend. Medians of D1X, D3 and D6 were calculated for all cases per disease and for all diseases together, for each of three periods: period 1 (P1): notification to MHS between July 2003 and Jan- uary 2009 (former law), period 2 (P2) between January 2009 and January 2013 and period 3 (P3) between January 2013 and November 2017. We divided the period with the new law in two equal periods to analyse delay trends in time.
Delay analysis
Median delays per disease per period, median delay of all cases per period and average of the medians of diseases in period 2 and period 3 were compared with period 1, using the permutation test [8]. This test uses the data to con- struct a null distribution and derive p values without making any a priori as- sumption on the distribution of the data. This is particularly useful when we are dealing with strongly right-skewed distributions, as is the case with delay times. Statistical calculations were performed on medians and means. Since there was substantial overlap in outcomes, we chose to present the outcomes on medians for reasons of clarity and representativeness. As the number of notifications per disease varied widely, averages of medians of delays per diseases were calculat- ed per period as well. Medians and boxplots were calculated per year for noti- fication and reporting delay to study trends over time within periods. Percent- age of diseases notified after 3 days (including weekend days) of most recent notifications in 2016–2017 were calculated for comparison with percentages calculated by Reijn et al. over period 1 [1].
Timeliness analysis
Heads of laboratories and physicians need to notify a notifiable disease within 1 working day to the MHS. The MHS needs to report a notified disease within 1, 3 or 7 days, depending on the disease, to the RIVM. In order to present the most up-to-date situation, we used notifications of 2016–2017 and calculated the percentage of notified cases within the legal timeframes per disease.
Other timeframes were based on serial intervals and incubation periods, as the duration of these intervals determines how fast an outbreak develops. Mid- points of the ranges of incubation periods for 10 person-to-person transmissible diseases were retrieved from the national guidelines of the RIVM and medians of serial interval distributions for eight of these 10 diseases were retrieved from literature [2,9,10]. Lastly, we included a timeframe for outbreak control calcu-