The definition and measurement of waiting times varies significantly across OECD countries, limiting the comparability of data. For non-emergency care, the measurement can use different start and end points. As shown in Figure 1.1 in Box 1.1, the waiting time can be recorded from the GP referral or following a specialist visit. It can end with a surgery or medical treatment, or with a specialist visit. Some health systems will measure what is sometimes referred to as the “outpatient” waiting time (from GP referral to specialist visit), others the “inpatient” waiting time (from a specialist decision to add the patient on the list to treatment), yet others measure the full referral-to-treatment waiting time (from GP referral to treatment), as is the case in Denmark, Norway and England.
For any health services, it is possible to measure and report the mean waiting time, the median waiting time or the waiting time at other percentiles of the distribution, and the number or proportion of patients waiting more than a threshold waiting time (for example 3, 6 or 12 months). The distribution of waiting times is generally skewed, with a small proportion of patients waiting a very long time. Hence, the mean waiting times can be substantially longer than the median.
Information on waiting times can be collected through administrative databases or surveys. One advantage of surveys is that they can often readily be used to measure any inequalities in waiting times across socio‑economic groups, but one downside is that the data may be less reliable particularly if the sample size is small and may also become outdated if the surveys are not conducted regularly.
Annex A describes in more detail good practices in some countries in setting information systems to measure waiting times.