The adjusted column was designed to avoid counting patients that have visited multiple clinics in a PHN catchment more than once. The number in the 'Adjusted' column is based on a 'virtual' patient to provide complete data without counting patients more than once. Patients who have visited more than one clinic in an organisation's catchment will be counted more than once in the organisation column (PHN or other) as their data is included in each upload from the individual clinics.
To identify patients that have been uploaded more than once we are using the Statistical Linkage Key (SLK) that is also in use by the Australian Bureau of Statistics (ABS). For a full definition of the key please see here: SLK Definition ABS website
This key is created when the extract is collected at the practice level and is encrypted before uploaded to PAT CAT. The SLK provides a way to identify duplicate (or more instances) of patient records, it importantly does not allow the identification of the patient. The SLK is not reversible and is purely used for the described purpose in PAT CAT. All data uploaded to PAT CAT is managed and used by the PHN or other organisation, PEN CS does not have access to or ownership of the data.
The 'Adjusted' column will use the most recent visit on record as a starting point for the virtual patient and remove all other instances of patients with more than one visit. Then PAT CAT will find missing/incomplete fields for the patient in the data uploaded from other clinics and attempt to complete the virtual record.
With PAT CAT version 3.3 and above we have introduced the following behaviour for a number of different patient statuses:
- If a duplicate patient is "Deceased" then virtual patient is marked as "Deceased"
- If any of the duplicate patients is status "Current", "Transient" or "Banned" then virtual patient is marked as "Active"
For example if you have a patient who visited 3 clinics who all uploaded their data to PAT CAT and only one of the three clinics has a diagnosis of diabetes on file, PAT CAT will use the patient record with the most recent visit date. PAT CAT will then go through all reported indicators and check if there are results missing from the most recent record. Anything missing from the original record will be completed using data from the other visits of the patient. If there is more than one result available, the most recent one is used.
This creates a single virtual patient with all available and most up to date information from all clinics visited in the current reporting period.
When used for the whole catchment (no Practice filters) this will normally show a lower number in the adjusted column as duplicates are removed. Based on current numbers this can be between 10 and 25% less patients as visiting more than one practice is very common.
Even when looking at all practices the numbers in the adjusted column can, under certain circumstances, be higher than the total. Consider this example:
- Filter for active patients with Asthma.
- A patient has visited multiple practices
- One practice has a diagnosis of Asthma recorded, the other doesn't - this means the virtual patient in the adjusted column has a diagnosis of Asthma
- The patient is an active patient (3 or more visits to one practice) - this means the virtual patient in the adjusted column is an active patient
- Now when you apply a filter for active patients with Asthma there will be none in the total but one patient in the virtual column
This is not always the case and depends on overall patient characteristics and data uploaded, but it is a scenario to consider when using the adjusted column.
However when you use a filter for one practice (or a group of selected practices) the adjusted column can show higher numbers as in the example below. The filters applied were for one practice and for patients with diabetes only. As you can see from the total there are 819 patients at the clinic but 1061 in the adjusted column.
The adjusted column was not designed for this function but it can provide interesting data as it enables the PAT CAT user to see information about patient groups that has been entered at other clinics than the one filtered for. It does not provide information where the information was entered, but it might still be useful for some research.
Generally we don't recommend to use the adjusted data for report when filtering by practice(s), but as the above example shows, there can be valuable information gained from this report when filtering for one practice.