MO060CYSTINURIA: DISEASE PRESENTATION, PROGNOSIS AND QUALITY OF LIFE ANALYSIS OF A WEB-BASED COHORT
Authors: Baccaro Rocco , D'Ambrosio Viola , Ferraro Pietro Manuel 
Published: May 2021

Background and Aims

Cystinuria is considered a rare condition as approximately 1% of adult and 6% of pediatric kidney stones are due to this defect. Prevalence varies by geographic region, with good representation in the Mediterranean area. Given the low prevalence and the lack of a defined clinical pathway for these patients, only partial data are available on the long-term course of the disease.

A group of cystinuria patients has gathered on Facebook to exchange advice on symptom management and therapy.

The use of this type of platform, in cases of low-prevalence diseases, is a good method of collecting patients who otherwise would be difficult to reach.

We proposed an online survey to further analyze clinical, therapy, and quality of life of cystinuria patients.

Method

An online survey was proposed to an Italian social media group restricted to cystinuric patients with the agreement of the administrator. Before participating to the survey, patients provided documentation on their diagnosis and signed an informed consent. The survey was structured in four sections: a thorough medical history focused on kidney stone and cystinuria, the SF-36 questionnaire, the Fatigue Severity Scale, The Brief Pain Inventory.

Data was managed and analyzed anonymously.

Results

Our survey was sent to 55 patients, but only 18 completed all questionnaires. Our cohort is composed of 5 men and 13 women, with a mean age of 39.5 years (SD 17.6), mean height 156.4 cm (SD 18.5), mean weight 60.8 kg (SD 17.9), mean BMI 24.1 (SD 4.5).

About medical history, 15/18 patients have had at least 4 episodes of renal sstons in their lifetime, of these 10/15 reported stone expulsion in most episodes. The first episode occurred on average at 14.9 years (SD 9.3), while confirmed diagnosis of cystinuria arises at 20.1 years (SD 15.1).

Most patients experienced bilateral stones (12/18). The diagnosis was confirmed generally by: stone composition analysis (39%), urinary cystine levels (24%), cystine crystals revealed at fresh urine exam (22%), genetic findings (7%), Brand test (2%), other (5%). About 33% of our cohort performed a genetic test.

Almost 95% of patients are in follow-up with a clinic. Routine exams include: renal ultrasound (30%), nephrologist evaluation (27%), urine 24h evaluation (25%), urology visit (13%), abdominal CT (4%), kidney x-ray (2%).

All the patients of our cohort received urological or surgical procedures for kidney stones: generally endoscopic procedures (32%), or lithotripsy (30%), or open surgery (23%). Four patients underwent a nephrectomy.

Patienst reportes an average of 31 painful episodes of renal colic (min 0; max 200) in their history. Of these episodes almost 6 ended with a stone expulsion (min 0; max 50), while haematuria was reported by 12 patients (up to 20 episodes in a patient lifetime).

A secondary stone composition in addition to cystine was reported by 5/18: calcium oxalate in 100% of these cases, even with struvite and calcium phosphate.

Most of these patients (78%) received some nutritional recommendation: generally by nephrologist (50%), or dietician (23%), or urologist (18%). Indications were not easy to follow: a 0-100 visual scale about compliance showed a mean of 45 (SD 27).

The 78% were currently on drug therapy: most used therapy included citrate (45%), tiopronin (40%), or bicarbonate (10%). Drugs compliance is very low (26/100 scale SD 23.3).

Nobody in our cohort showed a GFR of less than 60 mL/min/1.73 m2. 4/18 reported a positive family history of cystinuria, while 7/18 relatives with renal stones without a diagnosis.

Conclusion

Patients affected by cystinuria show a very poor quality of life, with high levels of pain, fatigue, and emotional wellness. The diagnosis is delayed from the first event, and they are exhausted by an high frequency of pain stone passages. More attention to quality of life aspects is needed in patients with this rare but life-threatening condition.