REPLY Modeling downstream effects (SD6661)

[SDMAIL Timothy D. Quinn]

Posted by  "Timothy D. Quinn" <tdquinn at MIT.EDU>

Dave,

No doubt others on this list will jump to provide references to relevant
models in the SD literature.  In particular, I like David Lane's study:

Lane, D. C., Monefeldt, C., & Rosenhead, J. V. (2000). Looking in the
wrong place for healthcare improvements: A system dynamics study of an
accident and emergency department. Journal of the Operational Research
Society, 51(5), 518-531.

One of my aborted dissertation projects was to model this problem for a
large academic medical center.  At the time, I concluded that a
discrete-event or hybrid modeling approach was necessary to capture
details that were relevant for policy design.  I built a big model in
AnyLogic (version 5.5), but data collection for parameterization turned
out to be infeasible (one reason: I would never graduate).

Goldratt's theory of constraints and SD both provide useful concepts --
stocks, flows, bottlenecks and their locations -- for iteratively trying
to improve inpatient flow.  Also relevant is the problem of variation in
patient lengths of stay and associated interarrival rates to the
different hospital units.  I believe the applicability of traditional
queuing theory to this problem is limited, but that hasn't stopped some
folks from trying to apply it:

McManus, M. L., Long, M. C., Cooper, A., Mandell, J., Berwick, D. M.,
Pagano, M., & Litvak, E. (2003). Variability in Surgical Caseload and
Access to Intensive Care Services. Anesthesiology, 98(6), 1491-1496.

McManus, M. L., Long, M. C., Cooper, A., & Litvak, E. (2004). Queuing
Theory Accurately Models the Need for Critical Care Resources.
Anesthesiology, 100(5), 1271-1276.

Litvak, E., Buerhaus, P. I., Davidoff, F., Long, M. C., McManus, M. L.,
& Berwick, D. M. (2005). Managing Unnecessary Variability in Patient
Demand to Reduce Nursing Stress and Improve Patient Safety. Joint
Commission Journal on Quality and Patient Safety, 31(6), 330-338.

This problem is so important that the Institute for Healthcare
Improvement has gotten in on the action
(http://www.ihi.org/IHI/Topics/Flow/).  Not to be outdone, I guess, I
received an email just this morning announcing a teleconference call by
The Joint Commission (formerly JCAHO) entitled "Managing Patient Flow:
Reducing Hospital Overcrowding".

Hope this helps,
-Tim
-- 
Timothy D. Quinn
PhD Candidate
System Dynamics Group
MIT Sloan School of Management 
Posted by  "Timothy D. Quinn" <tdquinn at MIT.EDU>
posting date  Wed, 10 Oct 2007 11:42:47 -0500