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Kidney Week

Abstract: TH-PO847

Self-Monitoring of Urine Specific Gravity Using Study Smartphone Applications Promotes Adherence to High Water Therapy and Facilitates Remote Data Capture in the DRINK Randomised Trial

Session Information

Category: Genetic Diseases of the Kidneys

  • 1001 Genetic Diseases of the Kidneys: Cystic


  • El- Damanawi, Ragada, Cambridge Clinical Trials Unit, Cambridge, United Kingdom
  • Harris, Tess M., Polycystic Kidney Disease Charity, London, United Kingdom
  • Mader, Laura B., Patient Led Research Hub, Cambridge, United Kingdom
  • Sandford, Richard N., University of Cambridge, Cambridge, United Kingdom
  • Wilkinson, Ian, Cambridge Clinical Trials Unit, Cambridge, United Kingdom
  • Karet, Fiona E., University of Cambridge, Cambridge, United Kingdom
  • Hiemstra, Thomas F., Cambridge Clinical Trials Unit, Cambridge, United Kingdom

High water (HW) intake inhibits vasopressin, a key promoter of disease progression in Autosomal Dominant Polycystic Kidney Disease (ADPKD). Maintaining HW intake requires patient motivation and commitment to self-management. We evaluated the role of a smartphone application to facilitate adherence in ‘DRINK’, a randomised feasibility trial of HW versus ad libitum water intake in ADPKD (NCT02933268).


We developed a cross-platform smartphone application for home monitoring and remote submission of twice weekly urine specific gravity (uSG) results by participants enrolled in ‘DRINK’. Participants targeted uSG ≤1.010 (HW) or >1.010 (AW). Fluid intake instructions were embedded in the app. Submitted data were transferred in real time to a central administration portal.


81% (34/42) of trial participants (HW n=16, AW n=18) used the app. Over the 8 week follow-up period, HW patients used the app to submit uSG data 92% (165/179) of the time compared to 91% (199/219) in the AW group, p=0.38. Baseline characteristics were similar between treatment arms amongst app users (female 53% vs 56% p=0.75, White British 81% vs 83% p=0.82, mean age 47±11 vs 43±11 years p=0.38, in the HW and AW groups respectively). Plasma osmolality was 290±9 (HW) vs 289±7 (AW) mOsm/kg (p=0.68) with a corresponding median uSG 1.010 IQR 1.010-1.015 (HW) and 1.010 IQR 1.010-1.015 (AW), p=0.52. Target uSG was achieved 79% of the time in the AW group and 80% in the HW group, p=0.75 (Figure).


Smartphone technology resulted in high levels of adherence to the study intervention, reliable remote data collection and attainment of target USG with separation between treatment arms. Incorporation of this methodology into future trials is feasible and enhances research efficiency.

Figure: Separation in urine specific gravity (left), smartphone app (right)


  • Government Support - Non-U.S.