Category: Clinical Stones: Outcomes

MP32-11 - The relationship between ethnicity and stone composition in a large multi-ethnic London NHS Trust

Sun, Sep 23
2:00 PM - 4:00 PM

Introduction & Objective :

Whilst the relationship between stone prevalence and ethnicity is known, we aim to identify if there is a relationship between ethnicity and stone composition.


Methods :

We did a retrospective review of all patients with laboratory stone analysis in 2017 at a large multi-hospital NHS Trust. Patient electronic records were reviewed to ascertain patient ethnicity, age and gender. Stone characteristics including size, location and composition were recorded. We also reviewed patients’ previous stones.


Results :

312 patients had laboratory stone analysis: 91 white British, 63 white other (16 eastern Europe, 6 western countries, 2 middle east, 39 unspecified), 94 Asian, 19 Black, and 45 others.


Calcium oxalate was the commonest stone type in all groups: (59-74%, overall: 64%) with calcium phosphate being the second most common (11-36%, overall:  21%). Uric acid stones were seen in 10% of patients (0-17%).  Cystine and struvite (magnesium ammonium phosphate) stones were rare, with 1% and 2% respectively within the whole cohort.


Using a Chi Squared analysis there was no significant difference between stone composition in different ethnic groups (p=0.095). However, uric acid stones do appear to be more common in the ‘White-other’ group at 17% compared to 10% white British, 6% Asian, 0% Black and 6% other/ unknown.


10% of patients had had a previous stone analysed on our records.  A statistically significant number of patients, 87%, had formed the same stone before (p=<0.0001 binomial test).  100% of patients with a calcium oxalate, uric acid and struvite stones had previously formed the same stone. Whereas this was much less common with cystine and calcium phosphate stones. 


Conclusions :

No significant difference was found in stone composition between patients with different ethnicities. This suggests a stronger role for environmental factors in influencing stone composition, for example socioeconomic and dietary factors.


It is very common to form the same stone again, however not 100% so repeat stones still need to be sent for analysis.


We would encourage other centres to review their stone composition compared to ethnicities to further aid the discussion as to whether there is a difference due to ethnicity or due to environmental factors specific to the location.

Sophie N. Vaggers

Foundation Doctor
Department of Urology, Whipps Cross University Hospital, London
London, England, United Kingdom

Ross M. Warner

Clinical Fellow
Department of Urology, Whipps Cross University Hospital, London
London, England, United Kingdom

Luke Forster

Specialist Registrar in Urology
Whipps Cross University Hospital, Barts Health NHS Trust
London, England, United Kingdom

Zubeir Ali

Department of Urology, Royal London Hospital, London
London, England, United Kingdom

Pallavi Pal

Consultant
Department of Urology, Whipps Cross University Hospital, London
London, England, United Kingdom

Stuart Graham

Consultant
Department of Urology, Whipps Cross University Hospital, London
London, England, United Kingdom