3.3 Stock-Outs in Dispensing Machines (via St. Jude)

3.3.1 Contributors:

Special thanks to Ben Moore, PharmD and Alex Rodriguez, MS of St. Jude Children’s Research Hospital for their continued insight and feedback in the construction of this material

3.3.3 Introduction

A “stock-out” can generally refer to inventory exhaustion from some dispensary. In large and/or busy hospital systems, stock-outs commonly occur in automated prescription dispensing machines. Stock-outs may bottleneck clinical services (with providers forced to wait for re-stocks of necessary medications) and often require technician time (and implicitly, money for the technician’s time).

Many medications may be understocked if they are a frequent, root cause of stock-outs. Space can be re-allotted within the machines, replacing rarely dispensed medications with those frequently responsible for stock-outs. One must also consider the possible necessity of stocking rarely used medications if necessary in emergency situations, dependent upon the needs of the department.

In this use case, you will examine data from three automated dispensing machines, exploring what inventory changes can reduce the number of stock-outs, using one calendar year of transaction data. You’ve been presented with five data sets: (1-3) with transactions from respective dispensing machines, (4) that outlines the department(s) primarily using each machine, and (5) that includes information about the use and emergency stocking status of a medication. Use any one of the transactional tables and the fourth, machine-to-department(s) crosswalk table to explore the data by following the below tasks:

Data Dictionary

Transactional Data

Variable Description
TransactionID Unique identifier for each transaction
Machine Identifier of dispensing machine
Day Date of transaction
Medication Name of medication dispensed
Type Type of transaction taking place, Withdrawal or Refill
AmtRemaining Amount of medication in machine after transaction taking place

Machines Data

Variable Description
Machine ID Identifier of machine, also present in transaction data sets
Department/Location Relevant department(s) using each machine

Medication Data

Variable Description
Medication Name, dose, and type of medication
Note Primary use or relevant applications of medication
Emergency Status Binary. Yes indicates that a medication must be stocked at all times

3.3.4 Tasks

3.3.4.1 Exploratory Data Analysis

  1. What variables exist in the transaction data? What are their distinct values and/or distributions (where respectively meaningful)?
  2. How would you define a stock-out in the presented data? How many stock-outs occurred in calendar year 2020 (CY2020) in your data set?
  3. List the distinct medications present in the data
  4. Do stock-outs ever occur when a medication has not been completely dispensed?

3.3.4.2 Inventory Analysis

  1. Define a “stock-out” as anytime a medication must be refilled, using the data’s Type field. If this definition is different than that used above, how often do stock-outs occur in your data set?
  2. Plot the distribution of the number of stock-outs for medications in your data set
  3. What suggestions would you offer to reduce stock-out frequency