Announcement of changes to IRIS Guidelines

The IRIS Board met on 26th July 2022 and one major agenda item was to discuss updates required to the IRIS CKD staging and treatment recommendations. All board members reviewed these documents ahead of the meeting and items were proposed for discussion at the meeting. Following the meeting, if agreement was reached that updates were required, working groups were charged with suggesting precise amendments to these guidelines which were then presented to the full board for approval.

Staging Guidelines:

The section relating to discrepancies between creatinine and SDMA was felt to be in need of updating to include mention of breed specific reference ranges for both creatinine and SDMA and instances recognised where SDMA is elevated because of non-renal disease (e.g. lymphoma) where creatinine is not elevated. Amendments to the education article on ‘Reassessment of "normal" values in dogs and cats with chronic kidney disease’ will be made to complement the IRIS CKD Staging Guidelines and this revised article will be published in the spring of 2023 to provide further details in this area.

Treatment recommendations for cats:

Four main changes have been introduced to the cat treatment recommendations. These are:

1. The recommendation that clopidogrel should be the first line drug recommended for cats with protein losing nephropathy considered at risk of thromboembolic disease and the removal of serum albumin (<2.0 g/dl) as a definitive trigger for such therapy.
2. The introduction of FGF23 as a means of assessing cats with serum phosphate concentrations within the IRIS target range for each stage to determine the need for dietary phosphate restriction (in Stages 1 and 2 where phosphate is in the target range at initial staging) or for enhanced restriction when initial dietary treatment has reduced serum phosphate into the target range. This follows the commercial availability of FGF23 as a diagnostic marker in the USA in 2022 and its expected availability elsewhere in the world in 2023. An in-depth education article on FGF23 has been written to accompany these changes.
3. The removal of the mention of calcitriol treatment for cats in the management of Stage 3 and 4 CKD due to lack of any evidence of a beneficial effect.
4. Introduction of a recommendation to treat stage 2 cats for vomiting/decreased appetite/ nausea/weight and/or muscle loss whilst recognising that SDMA might be used to stage cats with significant muscle loss and that investigations for concomitant diseases leading to vomiting should also be undertaken.

Treatment recommendations for dogs

The main changes introduced for the dog treatment recommendations were as follows:

1. In the management of proteinuria at all stages it was recommended that:
   a. Reduction of UPC below 0.5 was not possible in many patients with primary glomerular disease and that a more realistic treatment goal is a 50% reduction in UPC from pre-treatment baseline and to achieve the lowest UPC possible without causing harm
   b. Angiotensin receptor blockers should be the first line treatment rather than ACE inhibitors together with a clinical renal diet. This change is based on recent published evidence of randomised controlled clinical trials.
   c. There is no reliable predictor of thromboembolic complications of protein-losing nephropathy and that antithrombotic therapy cannot be guided by serum albumin concentration. The first line drug antithrombotic treatment should be clopidogrel with aspirin as an alternative.
2. An additional consideration has been inserted for dogs with stage 2 CKD and that is to treat suspected nausea and decreased appetite leading to weight and /or muscle loss.
3. The recommendation to use calcitriol treatment to manage bone mineral disorder in stages 3 and 4 has been removed. This decision came after some debate and was not unanimous. A majority of IRIS Board members felt that there was insufficient evidence to support this statement as a hard recommendation with some concerned that close monitoring, particularly of ionised calcium, that is necessary when using calcitriol treatment is not always easy to follow in general practice settings.