Daily examples to describe some problems around the resupply of items in a Pharmacy:
The most usual approach to organized supply of items seems to be
Minimum Level Reordering
In this case, (which introduces the concept of
reorder point), the reorder quantity can be fixed, but the frequency
of refills depends on the consumption.
This is like we go shopping (for a predetermined number on units)
immediately when we see we are short on some item.
In other cases, there may be a continuous (e.g. weekly) supply. In
this case the frequency is fixed, but the refill amount depends on the quantity needed . This is when we go monthly or weekly to a
big store - the amount we buy is usually variable.
Personally, like everyone, I think, I do not buy when the stock is below a given level. I note it in my list, and I consider the time between purchases and other factors to determine the quantity to buy.
More interesting for healthcare (but trivial to any person): when I go shopping, I take into account not only the current stock, and the usual stock, but also any additional factors that may influence e.g. the desired stock level - taking into account that I have one more person with me will increase the amount of food that I must buy.
This introduces the notions in Operations Research, where much advanced knowledge exists, and should be applicable to healthcare.
Healthcare logistics are still one step behind "normal" logistics, and the exploration of use cases should permit some innovation in healthcare.
Healthcare logistic shouldn't be considered one step beyong normal logistics. Several comment are needed for this post.
ReplyDeleteIn order to manage correctly your inventory, you need 2 thresholds: refill order point and minimum level. Refill order point : The standard level at which an item is refilled. If a supply gets at or below the refill point, it triggers request for refill. The refill point can be adjusted to reflect changing patterns of usage and demand. Minimum level : The level at which an item is considered unacceptably low and urgently needs refill.
Depending of usual consumption and refill frequency, the minimum quantity is a calculation that avoid stock-out events. At a second level, some consumption may be eractic with sudden peaks. Peaks need to be considered in oreder to adjust appropriately the minimum level and refill order point. At a third level, lead time need to be considered. A lead time is the latency (delay) between the initiation and execution of a process. For example, the lead time between the placement of an order and delivery of a medication from the pharmacy may be anywhere from 10 mn to 1 week.
Some existing algorythms helps to calculate these thresholds appropriately.
Aha! Merci!
ReplyDeleteBy no means I think that healthcare logistics should be different from normal logistics. I am looking at how complex and elaborate logistics are outside healthcare, and would like to see this applied to healthcare consistently.
I also agree with the reorder quantity is the most common way of addressing stocks. This, I think, is the (s, Q) inventory policy.
Indeed, these thresholds can be optimized given the inventory value, storage costs, lead time, risk of expiry, cost of ordering, discounts, etc.
Other techniques exist for correctly managing the inventory: One seems to be called the (R, S) inventory policy: Sometimes, the trigger for reordering is not a minimum stock: Sometimes the trigger is a weekly event.
Naturally these can also be combined.
My idea is that any supply mechanism should allow any kind of stock policy to exist.
Other ideas: In some situations we may predict when will the stock be reaching the minimum (looking at the appearance of 10 new prescriptions for patients, we can indicate that the consumption will increase).