There are a few thousand people with a claim in year 2 who have claims with fields set as follows:

Speciality: Surgery
PlaceSvc: Ambulance
Length of stay: 1 day
Nearly all have a three or four letter procedure code beginning with 'S' - i.e. confirmation they had surgery.

How can it be that so many have DIH as zero? The only thing I can think of is that they died after the surgery but before they spent a full day in hospital.

Day/Night Surgery is ambulatory (ie outpatient), no length of stay.

A number of surgeries which were previously performed as inpatient are now (sometimes) performed in outpatient services depending on Acuity, Age and other factors.

Unfortunately in some cases whether or not the patients are held overnight will depend on the policies of the performing organization and how close to best practices they run their surgery dept and of course (since it's fee-for-service) it might depend on whether or not they can bill for the over-night stays.

Interesting and relevant....

As a healthcare outsider, could you summarize what "ambulatory" care is? I had assumed it was simply an ambulance with a siren taking the patient to a facility, but clearly it means somethine else.

In a hospital setting Ambulatory Care is out-patient clinics and services (excluding Diagnostic Imaging, Radiology etc), sometimes including ER as a sub-set, but usually not as the Emergency Department costs and is run differently since clients appointments are un-scheduled.  The ambulatory clinics usually serve both inpatients and outpatients.

Aside from where ER's are included Ambulatory is almost never related to ambulances.

Thanks for the clarification.