The current study included a total of 1000 patients with SCI comprised of 87.2% males and 12.8% females with a mean age of 34.07 ± 13.19 years and a mean duration of SCI of 5.95 ± 5.84 years. This study revealed the advantage of the hydrophilic coated catheter over the PVC uncoated catheter. This difference was clearly shown with a low proportion of symptomatic UTI (46.6% versus 79.4%), bacteriuria (64.69% versus 81.09%), and pyuria (41.79% versus 53.57%) among the patients using the hydrophilic coated catheter compared to those using the PVC uncoated catheters. There was no significant difference between the two studied cohorts regarding age, gender, and co-morbidities as shown in Table 1.

There was a significantly lower proportion of UTI symptoms in terms of fever, spasticity, and cloudy urine among patients using the hydrophilic coated catheter compared with patients using PVC catheters. Additionally, patients using hydrophilic coated catheters had a significantly lower proportion of positive nitrate using urinary dipstick test and bacteriuria as shown in Table 2. As shown in Appendix S1, in supplementary material, the proportion of symptomatic UTI was significantly higher among the patients who were using PVC uncoated catheters across different age groups and the two genders, ASIA scale levels, SCI duration categories, and different numbers of co-morbidities, p < 0.001, except for ASIA scale D (p < 0.175) and more than three complications (p = 0.05).

When looking at the culture results, the patients using PVC uncoated catheters had significantly higher rates of bacterial species compared to the ones using hydrophilic coated catheters, at 72.89% versus 52.29% respectively. Escherichia coli was the most commonly isolated organism for patients using either coated or uncoated catheters, although it was more common among patients using uncoated catheters, while Klebsiella pneumonia was the second most common organism in the two groups of patients with no difference in frequency between the coated and the uncoated catheters users. Proteus mirabilis, Pseudomonas aeruginosa, and Enterococcus faecalis, all were isolated more frequently among patients using uncoated catheters. Staphylococcus aureus and Providencia stuartii have been noted to be more prominent in the coated catheter cohort. The other isolated bacteria were rare and demonstrated variability among both coated and uncoated catheter groups, please see Fig. 2.

The number of different isolated bacterial species from the two cohorts

When considering the age groups ≥ 25 years, 26–35 years and > 35 years, patients using coated catheters had less symptomatic UTI, bacteriuria, and pyuria compared to those who are using PVC uncoated catheters. Patients with symptomatic UTI, pyuria, and bacteriuria and using hydrophilic coated catheters were having significantly higher rates of males compared with PVC uncoated catheter users. Additionally, there was a higher frequency of class A and D among patients with symptomatic UTI, pyuria, and bacteriuria and using hydrophilic coated catheters, compared to the PVC uncoated catheters patients. On the other hand, patients using PVC uncoated catheters had higher rates of ASIA scale class C in three reported outcomes compared to the hydrophilic coated catheter patients as shown in Fig. 3.

Distribution of symptomatic urinary tract infection (UTI), bacteriuria, and pyuria by age (a); gender (b); and ASIA scale (c) among the study cohort according to the type of catheter

As shown in Table 3, the OR of developing symptomatic UTI was more than 12 times higher among the patients who used the PVC uncoated catheters compared to those who were using the hydrophilic coated catheters in the univariate analysis, OR [95% CI] (12.97 [8.0–21.0], P < 0.001). This association remained after conducting the multivariate analysis indicating that the association was independent of age, gender, duration of spinal cord injury, ASIA scale, and the number of comorbidities. This independent association was also observed between the uncoated catheter use and both pyuria and bacteriuria but to a lower extent with OR [95% CI] for the univariate analysis at 1.59 [1.2-2.0], p < 0.001, and 2.34 [1.7–3.1], p < 0.001 respectively.

When performing univariate logistic regression analysis, male gender, and ASIA scale level C or higher were associated with an increased risk of symptomatic UTI in the studied patients, where there was 84% higher OR for symptomatic UTI among men compared to women (OR = 1.84; 95% CI: 1.3–2.7), while ASIA scale ≥ C was associated with a 31–41% higher OR for symptomatic UTI. However, in the multivariate logistic regression analysis, only the male gender remained a significant risk factor. On the other hand, age ≥ 25 years and SCI duration ≥ 10 years were associated with reduced risk of symptomatic UTI, with this association being independent of gender, and the number of complications as shown in Table 4. As shown in Appendix S2, supplementary material, only having one complication was independently associated with an increased risk of pyuria, OR [95% CI], 1.4 (1.1–1.9), P = 0.011. None of the studied risk factors were associated with an increased risk of bacteriuria, except for ASIA scale ≥ C which was independently associated with a 40% increased risk of bacteriuria, as shown in Appendix S3, supplementary material.