Evaluation of manpower scheduling strategies at outpatient pharmacy with discrete-event simulation

Abstract

An outpatient pharmacy of a tertiary hospital in Singapore had uncertainty over the impact of different manpower scheduling strategies on the length of time (that is, cycle time) that their patients needed to spend during their visits. This article illustrated how this uncertainty could be addressed via application of discrete-event simulation (DES). Recent service rates of pharmacy staff and manpower allocation schedules were used to represent the process characteristics of the pharmacy in a DES model. On the basis of different new manpower scheduling strategies, the DES model projected quantitatively their respective impact on patient cycle times and manpower resource requirements. In this study, a new manpower scheduling plan, which matched manpower availability with patient arrival pattern, was recommended. On the basis of DES model projections, this recommendation could reduce both median and 95th percentile cycle times (39.7–45.7 per cent) with less than 7.5 per cent increase (or two new hires) in overall manpower requirement.

Appendix

Assuming that each pharmacy staff works 8 hours daily, the overall manpower requirement (OMR _s ) of a manpower strategy (s) was computed as follows:

where τ=0.25, p∈{registration, typing, packing, checking, dispensing}, t∈{0.25, 0.5, 0.75, …, 10}, and x _pt denotes the average number of staff in process p working during the period t. Note that t denotes the period between t-0.25 and t hours from the opening time of the pharmacy (that is, 08:00).

The percentage increase in overall manpower requirement of strategy s was computed relative to the overall manpower requirement in the validated model, which is denoted by OMR _v as shown in (A.2).