Influence of proBNP Testing on Clinical Assessment by Heart Failure Specialists

1. Influence of proBNP Testing on Clinical Assessment by Heart Failure Specialists Jones GRD, Macdonald P, Keogh A, Kotlyar E, Hayward C, Boscato L. Department of Chemical Pathology and Cardiology, St Vincent’s Hospital, Sydney.

2. Background • ProBNP concentrations correlate well with cardiac function and provide strong prognostic information. • Introduction of routine proBNP testing may have significant financial implications. • Unless proBNP results change clinical assessment or management, there will be little benefit provided by the testing.

3. Aim • To assess whether the provision of a routine proBNP testing service leads to changes in the assessment and management of patients by heart failure specialists.

4. Diagnostic test assessment 1. Technical quality of test 2. Diagnostic accuracy of test 3. Change in diagnostic thinking 4. Change in patient management 5. Change in patient outcome 6. Cost effectiveness of test Frybeck and Thornbury 1991 (J Doust AACB Hobart 2006)  

5. Methods • A weekly service for proBNP testing was provided to four hospital-based heart failure specialists. • proBNP was measured with a Roche Elecsys 2010 analyser. • The influence of the testing was assessed with pre- and post-test questionnaires. • The protocol was approved by the St Vincent’s Hospital Human Research Ethics Committee.

6. Questionnaires • Pre-test questionnaire • Used as the request form • Recorded the reason for the request • Recorded pre-test clinical assessment

7. Questionnaires • Post-test questionnaire • Provide the result • Together with requesting information • Reference intervals • supporting interpretive data • Questions on effect of the test result on patient assessment and management.

8. Population Reference Intervals (ng/L) MaleFemale 18 - 50 years <70 <120 50 - 65 years <180 <270 65 - 74 years <230 <350 75 + years <650 <850 Expected values of proBNP in classes of heart failure (ng/L) Class5th centileMedian95th Centile NYHA I 30 350 3,500 NYHA II 100 950 6,500 NYHA III 130 1,600 10,000 NYHA IV 150 1,700 12,000

10. Results and Comment (1) • 215 proBNP results were provided for 126 patients over 13 months. • Comment: Fewer than 20 samples per month were requested by these clinicians suggesting very targetted testing.

11. Results and Comment (2) • 134 patients had a single proBNP test • 46 had 2 tests • 23 had 3 tests • 19 patients had 3 or more tests. • Comment: A single tests was all that was required in many cases, although monitoring progress in patients was also common.

12. Results and comment (3) • Valid pre- and post-test questionnaires were received for approximately 70% of the sample. • Comment: The information acquired is a reasonable representative sample of all requests.

13. Pre-Test Questionnaire Requesting Reasons: 1. Assessment of cause of shortness of breath 2. Assessing severity of known heart failure 3. Assessing contribution of heart failure to symptoms in a complex patient. 4. Other indication. Further details: eg NYHA class

14. Reasons for Testing

15. Reasons for Testing Comment: The majority of requests were for assessing severity of known heart failure. Expected finding given the clinicians involved. Text notes indicated a large number where proBNP was used to guide therapy.

16. Post-test questionnaire In response to the proBNP result in this patient have you: 1. Supported your pre-test diagnosis / assessment 2. Changed or modified your pre-test diagnosis or assessment. 3. Raised further diagnostic possibilities 4. Made a change in the management plan

17. Effect of Testing

18. Effect of Testing

19. Effect of Testing Comment: ProBNP testing changed diagnosis, assessment or management in a large proportion of patients. Management was more likely to be changed after an initial test than after subsequent tests.

20. Management Changes • Increase in heart failure therapy (most common) • Reduction in therapy • Three patients were considered for either heart or lung transplantation

21. Confidence If “No” to question 4 (no change in plan) do you feel any change in your confidence in your pre-test management plan? • Less confident • No change • Slightly more confident • Significantly more confident

22. Clinical Confidence

23. Clinical Confidence

24. Clinical Confidence Comment: ProBNP testing increased confidence in clinical decisions in the majority of cases. Being less confident may also be a useful outcome.

25. Decision Points • Over 80% of the results were above the age and sex-related reference intervals. Comment • This reflects the population being tested. • Decision points other than population reference intervals may be required.

26. Confounders • Strong relationships were seen between proBNP results and age and renal function. Comment: Age and renal function must be taken into account. Serum creatinine should be measured with all requests.

27. proBNP v eGFR

28. Conclusions • When used by heart failure specialists, proBNP testing changed patient assessment and management in a significant proportion of cases. • When there was no change in patient management there was generally a greater confidence in the initial management plan. • This study does not address patient outcomes but indicates that proBNP testing provides additional information which is considered important by heart failure specialists

29. Acknowledgements This project was supported by a grant from the SydPath Research Fund and a donation of reagents from Roche Diagnostics Australia.