Study design, materials and methods
Study design, materials and methods: This is a cross-sectional study enrolling 18-year-old or older patients who underwent to kidney transplant in only one reference center. Patients with either non-functioning grafts or previous urological condition were excluded. The included patients answered three questionnaires: The Overactive Bladder questionnaire, short form with 8 questions (OAB-V8), the International Consultation on Incontinence Questionnaire, short form with 4 questions (ICIQ-SF) and the International Prostate Symptom Score with 7 questions (IPSS). The charts of the patients were reviewed as well.
The variables analyzed can be divided into demographic (gender and age), clinical (chronic kidney disease (CKD) etiology, comorbities, time of dialysis prior to transplant, smoking and alcoholism) and related to kidney transplant (type of donor, time since transplant, previous transplant, use of ureteral stent, induction of immunosuppression, total ischemia time, current creatinine, history of urinary fistula, delayed graft function (DGF) and cytomegalovirus (CMV) infection). The study was approved by the local research ethics committee (process: 2.750.468) and all patients have consented their participation and the use of their chart’s data.
The initial statistical analysis was performed through exploratory approach (frequencies to categorical variables and measure of dispersion to numerical variables). Then, Chi-square test (categorical variables) and ANOVA (numerical variables) were used in order to evaluate association between each potential risk factor and the scores of the questionnaires. The same variables and statistical analysis were also studied in different clusters: genders and age (less or more than 40 years old), looking for potential differences within groups, which could help us to understand global results. Any statistical difference observed was confirmed with multivariate analysis using regression.
Results: The studied took place in only one tertiary center between August 2018 and January 2019. Ninety-seven patients were evaluated but 80 fulfilled the criteria and were enrolled in the protocol. The main results are summarized in Table 1, where besides the global findings it’s shown the comparison between genders with its respective pValue and test chosen for each one (Table1).
There was statistical difference between genders only in alcoholism (male is more frequent) and current creatinine (women’s creatinine was lower than men’s).
As a whole, the mean scores observed in LUTS questionnaires were low (Table 1).
The percentage of patients who presented at least one lower urinary symptom varied widely according to questionnaire used. We observed 12.3% (n=9), 75.3% (n=60) and 98.8% (n=79) having some complain about LUTS in ICIQ-SF, OAB-V8 and IPSS questionnaires, respectively. Nocturia was the most common symptom in both IPSS (96.3% - n=77) and OAB-V8 questionnaires (66,7%-n=53). Storage symptoms (mean score1.95) were more common than voiding symptoms (mean score 0.77) using IPSS questionnaire as reference. However, even when present the symptoms seems to be neither severe nor bothersome. Moreover, urinary incontinence was rarely observed among transplanted patients, as 87.7% (n=71) scored zero in ICIQ-SF.
We found few associations between potential risk factors and mean scores of LUTS questionnaires. Patients with more than one kidney transplant presented ICIQ-SF mean score 7.6, while it was 1.05 for who had undergone only one (p< 0.010). The patients who hadn’t had CMV infection presented higher mean IPSS-score (11.6 x 6.5 – p=0.001) and OAB-V8 score (7.6 x 4.0 – p= 0.011) when compared with those with antecedent of CMV infection. Moreover, OAB-V8 score for alcoholics was 1.6, while for non-alcoholics was 7.0 (p<0.001). All of these results were confirmed in a multivariate analysis using regression tests.
There were no differences in mean scores of LUTS questionnaires when compared two age range (< or > 40 years old), although we observed the highest scores among older patients (Figure 1).
Interpretation of results
Interpretation of results: We observed low mean scores of LUTS questionnaires. It can be attributed to the composition of the sample, as approximately 50% of participants are less than 40 years old. Moreover, the mean time after transplant was about 60 months. We would expect the closer to the date of procedure the more probable of presenting LUTS. As we observe in studies with general population, storage symptoms, specially nocturia, are more common than voiding’s. The lack of difference between age ranges as well as potential risk or protective factors need to be confirmed in studies with larger samples and perhaps enrolling more than one center. Even though we hypothesized that patients who have undergone multiples transplants could present more LUTS because of excessive surgical manipulation of urinary tract. On the other hand, patients who treated CMV infections presented less LUTS than who not. It could be related to many drugs used on those patients which could have some effect over the urinary tract. Finally, it was observed lower OAB mean scores in alcoholics patients, what could have to do with the fact that alcoholics was more common in men and with the fact that the number of patients in this group was low.