Demand optimisation in diagnostics: standardising diagnostic testing in NHS Boards
Report highlighting current good practice, guidance on strategy and support for implementing demand optimisation.
Appendix D - Minimum Retesting Intervals Focus
Background
Unnecessary repeat testing represents wastage within scarce healthcare budgets. The concept of defining, where possible, time intervals whereby repeat testing would be unjustified, is one that could be useful for demand optimisation purposes. The Royal College of Pathologists have recently published guidance on Minimum Retesting Intervals in Pathology 1 (2015). This guidance serves as a baseline for laboratory services to define, in conjunction with their users, a strategy for limiting unnecessary repeat testing within their domain.
While some requesting interval blocking can be made at the laboratory/radiology department level, the most appropriate focus for improvement work would be the point of request, usually the clinical user's requesting interface - such as the order communications module - to ensure unnecessary test requests can be avoided before an order is made or a specimen taken. The early adoption of automated IT systems, as they are developed, should be encouraged. The actual mode of interaction will depend on the test in question, especially with regards to the volume of samples being received, the cost of the test and the clinical risks involved in actually blocking requests.
The National Demand Optimisation Group has recommended a workstream to explore and agree national minimum retesting intervals. The following information represents areas of key focus for each discipline, demonstrating existing variation in some cases. Note that some of these MRIs represent pragmatic compromises to ensure that important though rare indications for more frequent testing are not inadvertently blocked:
1. Clinical Biochemistry - MRI Times
| Test | NHS Grampian | NHS Fife | Comments |
|---|---|---|---|
| Vitamin D |
1 Year * |
** |
* only extremely rarely, a more ** Not available routinely in primary care. Only available when requested by key locations/consultants Any other circumstances contact duty clinical biochemist. Developing guidance |
| HbA1c |
1 week * |
60 Days |
* MRI can be extended if diagnostic and monitoring based testing can be distinguished - if so then the |
| Cholesterol |
1 month |
All lipids MRI |
|
| Thyroid Function Test |
1 week * |
28 days |
* MRI could be extended much further if clinical reason for request could be effectively interrogated via the order comms interface |
| CRP |
20 hours * |
48 hours |
* Essentially a one day MRI in practice. Note some boards have implemented |
| Liver Function Test |
20 hours * |
No MRI for LFT's |
* Essentially a one day MRI in practice |
| Transferrin |
28 days |
2. Haematology - MRI Times
| Test | NHS Grampian | NHS Fife | Comments |
|---|---|---|---|
| FBC |
20 hours * |
* Essentially a one day MRI in practice |
|
| INR |
20 hours * |
* Essentially a one day MRI in practice |
3. Immunology - MRI Times
In NHS Tayside, all requests that fall inside the minimum retest interval are electronically held on LIMS system and scrutinised by a senior member of staff (Band 7 and above) before rejection or acceptance. This protocol allows clinical context to inform decision.
| Test |
Current Retest interval |
Comments |
|---|---|---|
| Anti- TPO Abs |
12 months |
Repeats not routinely required |
| Anti- TRAB |
12 months |
Dependant on clinical context |
| Anti Gastric Parietal antibodies Intrinsic Factor antibodies |
12 months |
Repeats not routinely required |
| Anti-adrenal antibodies |
12 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Anti-Smooth muscle antibodies Anti-mitochondrial antibodies Anti-M2 antibodies Anti Liver Kidney Microsome antibodies |
6 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Anti-Neuronal antibodies |
12 months |
Repeats not routinely required |
| Anti glomerular basement membrane antibodies |
4 weeks |
Case by case basis for patients on therapy |
| Circulating skin antibodies |
6 months |
With discretion for patient on therapy for bullous pemphigoid |
| Anti tissue transglutaminase antibodies |
6 months |
frequency to be determined by clinical context |
| IgG endomysial |
None |
Only measured in patients with IgA deficiency |
| Anti nuclear antibodies ( ANA) |
6 months |
6 months |
| Anti-neutrophil cytoplasmic antibodies ( ANCA) |
4 weeks |
Case by case basis for patients on therapy |
| MPO/ PR3 |
42 days |
Case by case basis for patients on therapy |
| Anti ds DNA antibodies |
3 months |
Case by case basis for patients on therapy |
| Anti-Extractable nuclear antigens ( ENA) |
12 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Anti-cardiolipin antibodies |
9 weeks |
9-12 weeks retest to confirm positive results Previously negative determined by clinical context |
| IgM Rheumatoid factor |
12 months |
Not routinely required-frequency to be determined by clinical context |
| Anti- cyclic citrillullated peptide antibodies ( CCP) |
12 months |
Not routinely required-frequency to be determined by clinical context |
| Complement C3 and C4 |
4 weeks |
frequency to be determined by clinical context |
| lymphocyte subsets |
1 week |
All repeats must be discussed with consultant |
| Functional antibodies |
2 years |
Repeats to assess response to immunisation at 6-8 weeks on patients with previous levels below protective range. |
| Total IgE |
6 months |
For ABPA to assess efficacy of therapy |
| Allergen specific IgE |
6 months |
For ABPA to assess efficacy of therapy |
| IgG precipitins |
6 months |
For ABPA to assess efficacy of therapy |
| NMO Ab |
12 months |
Repeat testing guided by clinical context and only allowed if Oxford clinical questionnaire is completed |
| Basal ganglia Ab |
24 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| C3 nephritic factor |
12 months |
Not routinely required if positive, only allowed if C3 below normal range |
| GAD |
12 months |
Not routinely required |
| Ganglioside Ab |
12 months |
Not routinely required |
| Histone Ab |
12 months |
Not routinely required |
| IA2 Ab |
12 months |
Not routinely required |
| IgG subclasses |
12 months |
Not routinely required IgG4 - Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Mast cell tryptase |
28 days |
frequency to be determined by clinical context re anaphylaxis versus mastocytosis monitoring |
| MAG Ab |
12 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Myositis panel |
12 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| NMDA |
3 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Ovarian Ab |
12 months |
Not routinely required |
| Parathyroid antibodies |
12 months |
Not routinely required |
| Voltage gated KC and CC Ab |
6 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| Anti-acetyl choline receptor antibodies |
12 months |
Frequency determined by clinical context - every 6 months on treatment |
| Anti- MUSK antibodies |
12 months |
Repeat testing of limited clinical value -frequency to be determined by clinical context |
| C1 inhibitor protein and activity |
no limit |
Once only to confirm, generally only performed if C4 is low or with compatible clinical information |
NHS Grampian information-
| ANA/ CTD Screen / ENA Screen |
6 months |
|---|---|
| Liver Autoantibodies |
6 months |
| IgA anti- TTG antibodies |
12 months |
| Thyroid peroxidase antibodies |
12 months |
4. Microbiology/Virology - MRI Times
In general minimum tests intervals have not been implemented for Microbiology and Virology. The RCPATH guidelines for Minimum Retesting are based on expert opinion and as they are not being widely used there is an opportunity to formally validate them before being implemented.
There are some tests where there is established guidance on when to repeat the tests and labs do police the guidelines. These tests are a tiny percentage of the workload e.g. Viral load testing in HIV and retesting patients who are known to be positive for clostridium difficile.
There are large volume tests where MRI would be useful to reduce duplicate samples. Urine culture is an example. This topic needs to be discussed by the SMVN.
| Test |
Current Retest interval |
Comments |
|---|---|---|
| Viral load testing in HIV |
Depends on indication see BHIVA guidelines http://www.bhiva.org/documents/Guidelines/Monitoring/2016-BHIVA-Monitoring-Guidelines.pdf |
A small numbers expensive test where it is worthwhile enforcing guidelines |
| Clostridium Difficile testing |
Some labs will not test a sample if there has been a previous positive in the last 10 days |
NHS Grampian information-
| ASO Tite |
14 days |
|
|---|---|---|
| Helicobacter pylori serology |
28 days if previously negative |
Never repeat if previously positive |
| MRSA Screen |
7 days |
|
| Urine microscopy and culture |
3 days |
5. Radiology - MRI Times
In imaging there is very little in the way of minimum retesting intervals. Repeat radiological investigations would be subject to IRMER regulations. Imaging benefits from global work lists, so investigations performed in other boards would be visible to all NHS Scotland staff so duplicate tests should not be performed unless clinically necessary and within guidelines.
The only exception highlighted to the NDOG is chest X-ray for improvement of appearances of infection for which the patient has been prescribed antibiotics. There is little point in re x-raying in less than 7 days as the antibiotic course will not have been completed. However the patient may need to have further chest X-Ray if the clinical condition worsens so a degree of clinical judgement will need to be applied in some cases.
Contact
Email: Karen Stewart
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