Outpatient to Inpatient

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					                            Supporting your commitment to excellence

      Does Growth in GP referral link directly to growth in
                      inpatient demand?

                                    Dr Rod Jones (ACMA)
                                      Statistical Advisor
                               Healthcare Analysis & Forecasting
                                         www.hcaf.biz

The national planning assumptions make a direct link between growth in GP referral
and additions to the inpatient waiting list. While this may seem a reasonable
assumption there are certain instances where this is not widely applicable.

To understand why this is so we need to understand the forces regulating the growth
in GP referral and then look at the impact of GP referral thresholds upon the
conversion rate of first outpatient attendances to additions to the waiting list.

Growth in the Medical vs. Surgical Specialties

The following table gives the average growth in GP referral over the six years
1995/96 to 2000/01.

                                                                 Average
 Code                             Specialty                    annual growth
 823                              Haematology                     14.3%
 301                              Gastroenterology                12.5%
 320                              Cardiology                      10.9%
 303                              Clinical haematology            10.2%
 302                              Endocrinology                   10.0%
 361                              Nephrology                        9.8%
 310                              Audiological medicine             8.4%
 360                              Genito-urinary medicine           8.1%
 190                              Anaesthetics & Pain Relief        6.2%
 300,301,320,330.302,361          Medical Specialties               5.5%
 800                              Oncology                          5.0%
 420                              Paediatrics                       4.2%
 101                              Urology                           4.1%
 130                              Ophthalmology                     3.8%
 400                              Neurology                         3.5%
 300                              General medicine                  3.0%
                                  Average All Specialties           2.5%
 502                              Gynaecology                       2.3%
 430                              Geriatric medicine                2.3%
 330                              Dermatology                       2.3%
 140                              Oral surgery                      2.2%
 100,101,120,140,150,160,502      All Surgical Specialties          2.1%
 100                              General surgery                   1.9%
 150                              Neurosurgery                      1.8%
 110                              Trauma & Orthopaedics             1.7%
 340                              Thoracic medicine                 1.5%
 160                              Plastic surgery                   1.0%
 120                              ENT                               0.9%
 410                              Rheumatology                      0.8%
 510                              Obstetrics A/N                   -0.3%
 143                              Orthodontics                     -2.1%



© Dr Rod Jones (2006)      +44 (0)1276 21061                                     Page 1 of 5
                         Supporting your commitment to excellence

This table clearly shows the clear difference between the surgical specialties (which
tend to follow demographic change) and the medical specialties (which tend to grow
at twice the level implied by demographic change).

There are a few exceptions which can be easily explained:

    •    Data reporting issues rather than real trends
            o Urology shows higher growth due to its increasing prevalence as a
                specialty separate from General Surgery.
            o Gastroenterology and Cardiology shows higher growth due to their
                increasing prevalence as specialties separate from General Medicine.
    •    Mixed specialties
            o Ophthalmology shows growth intermediate to the Surgical and
                Medical specialties. This is due to the fact that only 20% of the
                Ophthalmology outpatient flow is due to surgical management (i.e.
                cataract) while the remaining 80% is due to the medical management
                of conditions.

Hence in conclusion the surgical specialties tend to show growth in GP referral which
is driven by demographic changes. As such growth is typically less than 2% per
annum.

Specialties with a mainly medical emphasis tend to grow at around twice the rate
implied by demographic changes.

Obstetrics has a clear demographic linkage for obvious reasons.

The Conversion Rate from First Outpatient Appointment to Inpatient

In the national planning assumptions this conversion rate is assumed to be relatively
constant. A better understanding of this process is required in order to understand why
this assumption is not a true reflection of actual practice.

GP referral thresholds

The decision to refer by a GP is commonly seen as having a threshold. This threshold
is influenced by:

    1.   Outpatient waiting times
    2.   PCT funding
    3.   Social trends
    4.   GP experience
    5.   Patient persuasiveness
    6.   Access to alternative options such as GPwSI or physiotherapy, etc

To demonstrate that there are large differentials in the threshold for referral we can
look at the outcome of GP referrals at a practice level.




© Dr Rod Jones (2006)   +44 (0)1276 21061                                            Page 2 of 5
                                                                Supporting your commitment to excellence

This is illustrated in the following chart where it can be seen that the effective referral
threshold exhibited by different practices reflects in the % of patients who are added
to the inpatient waiting list and on the % of patients who are discharged back into the
care of their GP. In this instance practices at the left hand side of the chart have a very
high referral threshold and presumably have access to supporting services from
GPwSI or in-house physiotherapy. Practices at the right hand end have a very low
referral threshold and consequently have corresponding low conversion rates from
outpatient to inpatient.

                                                                  Orthopaedic first attendance by GP practice

                                                 60%
  % Added to waiting list at first appointment




                                                 50%




                                                 40%




                                                 30%




                                                 20%




                                                 10%




                                                 0%
                                                   10%   15%        20%       25%         30%        35%        40%   45%   50%
                                                                      % Discharged back to GP at First appointment



The first point to note is that there are considerable differences in the referral
threshold between practices and the resulting relationship is non-linear. It is this non-
linear behaviour that can lead to shifts over time in the overall conversion rate –
which is the average of the thresholds of all practices referring into a particular
hospital.

The next chart demonstrates that such shifts do occur over time and these shifts can
lead to considerable change in the overall conversion rate.




© Dr Rod Jones (2006)                                          +44 (0)1276 21061                                            Page 3 of 5
                                                                                                  Supporting your commitment to excellence

                                                                                                                           ENT
                                                                                                         Conversion rate of outpatient to inpatient

                                                       33%
  % first attendance added to inpatient waiting list
                                                       31%


                                                       29%


                                                       27%


                                                       25%

                                                       23%


                                                       21%


                                                       19%


                                                       17%

                                                       15%
                                                         Nov-98             Feb-99                May-99             Aug-99              Dec-99                Mar-00             Jun-00                 Oct-00              Jan-01                Apr-01




Note also the considerable scatter from month to month which also leads to
uncertainty in the annual value.

Evidence that Inpatient demand is not directly linked to outpatient demand

The above charts strongly suggest that inpatient demand may not be directly linked to
outpatient demand. In practice the observed behaviour of inpatient demand is that it
tends to follow a discrete trend irrespective of the vagaries of GP referral.

This can be demonstrated by plotting inpatient demand over longer time frames
during which GP referral volumes have significantly fluctuated.


                                                                                        Orthopaedic GP referrals and Inpatient demand

                                                       9000

                                                       8000
                                                                                                                                  GP
                                                                                                                                  referral
                                                       7000

                                                       6000
   Annual demand




                                                       5000                                                                                   Inpatient
                                                                                                                                              Demand
                                                       4000

                                                       3000

                                                       2000

                                                       1000

                                                          0
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© Dr Rod Jones (2006)                                                                        +44 (0)1276 21061                                                                                                                                           Page 4 of 5
                         Supporting your commitment to excellence

As can be clearly seen in the above example for Orthopaedics the inpatient demand
trend is independent of the trend in GP referrals. The reasons behind this have been
explained above.

In conclusion, the assumed linkage between growth in GP referral and growth in
inpatient demand assumed within the national planning assumptions can be
questioned.

This assumption leads to a perceived need for higher levels of inpatient resource than
is the real case.




© Dr Rod Jones (2006)   +44 (0)1276 21061                                          Page 5 of 5

				
DOCUMENT INFO
Description: Investigates the factors behind the conversion ratio of outpatient attendances resulting in an inpatient admission. The conversion ratio is very much a factor of the quality of GP referrals sent to the hospital and the first outpatient attendance can be seen as a step in which many referrals are sent back to the GP for management in primary care.