# Wait times and Mortality

Does waiting longer for a medical appointment increase mortality? According to Julia Prentice and Steven Piezer’s 2007 article it does. The authors have data regarding individual wait times for Veterans Affairs (VA) geriatric visits as well as subsequent mortality data on each individual.

There are two major problems when trying to link increased wait times with increased mortality. The first is what the authors term a triage effect. Medical office staff often will allow sicker patients to skip to the front of the line and get a quicker appointment; thus, one could erroneously believe that increased wait times ceteris paribus decrease mortality. The other issue is that of selection. Sicker individuals may expend more effort to find clinics with shorter waits and thus one could again find that wait times and mortality are negatively correlated.

To control for these problems, the authors uses a measure of the predicted wait time of each patient rather than the patient’s actual wait time. The wait time is estimated for each “parent station” (e.g.: a medical center) based on the wait time per appointment type multiplied by the inverse of the frequency of the appointment type at the parent station. [Wait=Σiwaiti*(Freq[i])-1]. The authors note that there is some seasonal variability in wait times, but most of the variation is across facilities. The authors also try to control for observable health characteristics by including measures of individual disability, preventable hospitalization in the year prior to the first observed geriatric visit, and the Charlson index.

The authors use a random effects logit regression where wait time is divided into two periods: <31 days or >/=31 days. The authors also run a heteroskedastic probit model as well. The results of the regression are as follows:

Veterans who visited a facility with a 3-month average wait of 31 days or more were 21 percent more likely to die compared with veterans who visited a facility with a 3-month average wait of <31 days.

The authors note that health condition and disability are much better predictors of mortality than wait times, however. Also, one concern is that wait times per se are not affecting mortality, but simply that wait times are a proxy for whether a parent station is efficiently run or not. Lower wait times also may be strongly correlated with the local neighborhood’s average affluence or education level, both of which are correlated with mortality.