1. Creatinine methods and eGFR reporting in the SW and Wessex Region of the ACB Introduction The NSF for Renal Services recommends that for the NHS in England, from April 2006 all Clinical Biochemistry laboratories should report estimates of GFR alongside measurements of serum creatinine as an aid in the diagnosis and management of chronic kidney disease. Inter-laboratory variation in bias of creatinine methods causes significant differences in estimates of GFR that can result in different CKD stage classification. There is a need to minimise inter-laboratory differences in serum creatinine measurements, as patients are often transferred from one hospital to another during the management of CKD. We thought that it would be useful to conduct a survey of current practice within the SW and Wessex region of the ACB. A questionnaire on creatinine methods and current implementation if eGFR reporting was sent to 20 laboratories in the region in early June 2006 and replies were received from 17. This poster summaries the responses to that survey. Part I Creatinine Methods Laboratories were first asked about the methods used for the routine analysis of creatinine, including the number and type of analyser used, source of reagents and particular method employed. Information was also sought on steps taken to minimise analyser bias and to compensate for interferences as well as details of overall imprecision. What analyser(s) is/are used for routine measurement? Fig.1 shows the analyser manufacturers used and the number of laboratories using each but not the different models used. Do you use more than one analyser? This question was intended to discover the number of actual instruments used, but replies can not be categorised simply as ‘yes’ or ‘no’ and are summarised below. No – assumed only 1 instrument 1 No – Roche users with than one ‘P’ module 3 Yes – two or more identical instruments9 Yes – different instruments (same manufacturer) includes those with Roche ‘D’ and ‘P’ modules4 What measures do you take to minimise analyser bias? Identical (traceable) calibrators / reagents2 With QA/ QC and shared samples4 With IQC and EQA samples3 Not applicable2 None (but indicate no significant difference between instruments)4 No response to question 2 Who is the manufacturer of your reagents, are they used according to the manufacturers protocol? One Bayer user uses reagents supplied by Audit Diagnostics according to Audit protocol. The remaining laboratories use reagents provided by the instrument manufacturer according to the manufacturers’ protocols. Which methodology is used? See Fig. 2 - answers recorded precisely as given in the responses Is the method compensated for interferences? Yes – 14 No – 2 Correction factor - 1 What is your assay imprecision in the range 70-130 unol/L Fig 3 shows a scatter plot of the figures reported Fig 1 Fig 2 Fig 3 Part II Implementation of eGFR The first batch of questions sought to ascertain how many, when, and using what formulae, laboratories had implemented the reporting of eGFR. Of the laboratories that responded 14/17 had already implemented automatic reporting of eGFR. Of the three that had not, all cited IT issues as a reason for failure to implement, combined with certain cost issues. Two of these three said that implementation was pending but the third gave no such indication and gave under-funding of GP access work as a reason. Of those laboratories that had implemented, one had done so back in November 2004 and another in October 2005 but for the majority (9/14) implementation had been within a 3-4 week interval around 1/4/06, with the remaining three implementing in May and June. The auspicious date of 6/6/6 had been chosen by one laboratory and one of the three not yet reporting planned to do so from 30/6/06. Of the 15 sites already implementing (or about to) all but one were using the 4 variable MDRD calculation, and the other apparently a 3 variable (a typo?); 11/15 were using 175 as the constant in the formula and 4/15 were using 186. The use of constant was not linked to the creatinine methodology employed but was linked to the use of method specific slope and intercept adjustments; with all four respondents using the 186 factor replying that they did not use such adjustments. Two of this group indicated that the use of this factor was under review and, in one case, going to change with the introduction of new analysers. All but one (who gave no reply to the question) of the remainder do use slope and intercept adjustments. Next we sought to determine reporting criteria, e.g. what was reported, to whom and what interpretation was provided. Only 3/15 (these replies include the laboratory about to start reporting) calculate and report eGFR on all creatinine requests. Various exclusions were employed by the remainder. Seven labs were reporting on all adult (i.e. patients aged 18 or over) samples, irrespective of the origin of the request. Four were not reporting on most inpatients; two were only reporting on GP and OP patients, one on GP and G.U.M. patients and one on GP and renal unit patients. For one respondent the excluding factor appears not to be the source of the request but the result, with only eGFRs of 90’. All laboratories report eGFR alongside the routine ’U&E’ results, but only five report the CKD stage with the eGFR calculation, whilst 9/15 provide a multiplication factor to applied for African-Caribbean patients. We asked what other interpretative comments were issued on reports. If repetition of answers to previous questions is excluded, 4/15 offer no further interpretation; 3/15 have issued requesters with detailed guidance/guidelines and so provide no interpretation on reports. Two laboratories provide a hyperlink to renal physicians intranet/websites whilst two initially no longer provided comments but no longer does, one now gives only the www.renal.org address on reports and the other the African-Caribbean multiplication factor. The remaining five laboratories give varying degrees of interpretation, from single ‘catch-all’ comments regarding exclusions, CKD stage, referral criteria etc. to tailored comments generated automatically and based on the result. At least three of these also include the renal.org address in their comments. According to the answers provided only four laboratories specifically comment on the groups for whom eGFR is not recommended. 5/15 respondents told us that they had NOT agreed referral criteria with their local renal physicians. All but one laboratory participates in an appropriate EQA scheme with five belonging to both UKNEQAS and WEQAS schemes. Finally we asked about charging for eGFR calculation/reporting Only one laboratory is currently charging (£1) for eGFR but the one introducing it on 30/6 will also be charging £1, four more are planning to charge or ‘thinking about it’ and the remaining nine do not charge. Charging for eGFR does not seem linked to Foundation Trust status.Comments The purpose of this survey was merely to gather information about eGFR reporting within the region, and is not actually an audit. However as the results do show variation in methodology and reporting criteria it may be appropriate to conduct an audit based on the regional compliance with the NSF. It is clear, for example that the recommended implementation date was not adhered to, with two laboratories still not reporting eGFR because of IT difficulties and cost pressures. Recommendations on the amount of guidance issued with results are also not adhered to consistently amongst our respondents, in particular the requirement to communicate the need to apply a factor for patients of African Caribbean origin. Most of the laboratories serve only one renal unit but 2 renal units are served by more than one laboratory with the Portsmouth unit served by five. In such a situation it is recommended that laboratories provide comparable creatinine results, ideally by the use of identical methodology. In the case of the laboratories serving the Portsmouth unit four different instrument manufacturers are used, with three different methods and two different factors. Given the data available (not least in recent discussions on the ACB mailbase) on the effects such variations can have on the reported eGFR and subsequently on the CKD stage and the need for referral / further investigations this could be a cause for concern. Another area of concern, expressed in some of our replies, was that of the impact on laboratories, particularly in cost terms, of the increase in requests for analyses such as vitamin D and PTH following on from the implementation of eGFR reporting. Again this may be an area where collaboration and consensus could be useful, particularly in our negotiations with the PCTs. Perhaps a dedicated audit meeting on the topic, with an intent to try and harmonise practice, may be of value.