The use of urologic investigations among patients with traumatic spinal cord injuries

Figures & data

Table 1 Cohort demographics

	Entire cohort (N=1,551)
Sex (male), % (n)	74 (1,144)
Median age in years at time of TSCI, n (IQR)	48 (33–63)
ADG comorbidity score, %
0–11 (lower comorbidity)	77
≥12 (higher comorbidity)	23
Ontario marginalization scores quintiles
Residential instability	Q1 20%, Q3 15%, Q5 16%
Material deprivation	Q1 18%, Q3 19%, Q5 14%
Ethnic concentration	Q1 13%, Q3 15%, Q5 24%
Level of SCI, % (n)
Quadriplegia (cervical lesion)	37 (573)
Paraplegia (thoracic/lumbar lesion)	43 (663)
Missing RCG code	20 (315)

Note: For the Ontario Marginalization score, Q1 is considered highest SES, and Q5 is the lowest SES group.

Abbreviations: ADG, aggregated diagnostic groups; IQR, interquartile range; SES, socioeconomic status; TSCI, traumatic spinal cord injury; SCI, spinal cord injury; RCG, rehabilitation client group.

Table 2 Number of TSCI patients who had at least one urodynamic study, renal imaging test, or cystoscopy performed after a minimum of 1–5 years of follow-up

	After 1 year of follow-up (n=1,551)	After 2 years of follow-up (n=1,356)	After 2 years of follow-up (n=1,356)	After 4 years of follow-up (n=969)	After 5 years of follow-up (n=778)
Proportion of TSCI patients who had at least one urodynamic study	41% (631)	53% (712)	57% (662)	60% (580)	64% (496)
Proportion of TSCI patients who had at least one renal imaging study	60% (938)	80% (1,087)	87% (1,006)	91% (885)	97% (761)
Proportion of TSCI patients who had at least one cystoscopy	34% (533)	46% (619)	52% (600)	56% (545)	63% (487)

Notes: The size of the cohort decreases as the minimum follow-up increases as patients are censored due to death, emigration, or lack of minimum follow-up. Patients may or may not have investigations in each follow-up year, so the columns do not total to the sample size.

Abbreviation: TSCI, traumatic spinal cord injury.

Table 3 Time between successive urologic tests among the cohort of TSCI patients

	Time to first test	Time between first and second test	Time between second and third test	Time between third and fourth test	Time between fourth and fifth test
Urodynamics
Number of patients	775	433	239	155	90
Time in years, median (IQR)	0.26 (0.16–0.61)	0.48 (0.25–1.00)	1.00 (0.52–1.52)	1.02 (0.59–1.52)	1.01 (0.67–1.47)
Renal imaging
Number of patients	1,237	955	734	566	418
Time in years, median (IQR)	0.21 (0.06–0.91)	0.44 (0.16–1.07)	0.57 (0.22–1.25)	0.55 (0.17–1.04)	0.58 (0.25–1.11)
Cystoscopy
Number of patients	751	401	248	153	107
Time in years, median (IQR)	0.38 (0.22–1.29)	0.84 (0.33–1.16)	0.91 (0.4–1.42)	0.87 (0.42–1.38)	0.92 (0.41–1.25)

Note: The number of patients refers to the number of TSCI patients who had the specified number of repeat tests.

Abbreviations: IQR, interquartile range; TSCI, traumatic spinal cord injury.

Table 4 Event rate for urologic tests

	Initial test rate (within the first year) (per person-year of follow-up)	Overall test rate (per person-year of follow-up)
Urodynamics	0.41	0.22
Renal imaging	0.60	0.60
Cystoscopy	0.34	0.22

Notes: Initial tests are calculated based on the number of patients who received at least one test in the first year. Overall test rate is calculated from the total number of procedures divided by the total follow-up time.

Figure 1 The proportion of patients who maintain a yearly (A–C), or 2-year (D–F) pattern of investigation.

Note: The number of patients used to calculate the frequency of testing decreases as the successive minimum number of years of follow-up increases from 1 (n=1,551) to 5 years (n=778).
Abbreviation: TSCI, traumatic spinal cord injury.

Table 5 Cox proportional hazards model showing the relative hazard of receiving urodynamics, renal imaging, or cystoscopy

	Urodynamics	Renal imaging	Cystoscopy
Age group (reference category is 18–39-year olds)
40–64 years	HR =0.92 (0.77–1.09, P=0.34)	HR =0.91 (0.79–1.05, P=0.20)	HR =1.13 (0.95–1.36, P=0.17)
≥65 years	HR =0.63 (0.49–0.82, P<0.01)	HR =0.93 (0.78–1.12, P=0.45)	HR =0.91 (0.71–1.17, P=0.45)
Sex (reference is female)
Male	HR =0.85 (0.70–1.03, P=0.09)	HR =1.03 (0.89–1.19, P=0.71)	HR =1.12 (0.91–1.37, P=0.26)
ADG score (reference is 0–11, low comorbidity)
≥12, high comorbidity	HR =0.72 (0.58–0.89, P<0.01)	HR =1.04 (0.90–1.22, P=0.58)	HR =0.90 (0.73–1.11, P=0.33)
Ontario marginalization indexa
Instability	HR =0.98 (0.92–1.04, P=0.42)	HR =1.00 (0.96–1.05, P=0.90)	HR =0.98 (0.92–1.04, P=0.46)
Deprivation	HR =0.99 (0.93–1.06, P=0.81)	HR =1.01 (0.96–1.06, P=0.86)	HR =0.99 (0.92–1.05, P=0.64)
Ethnic concentration	HR =1.02 (0.97–1.08, P=0.48)	HR =1.05 (1.00–1.09, P=0.05)	HR =1.11 (1.05–1.18, P<0.01)
Lesion type (reference is paraplegia)b
Quadriplegia	HR =0.74 (0.62–0.87, P<0.01)	HR =0.80 (0.70–0.92, P<0.01)	HR =0.83 (0.70–0.98, P=0.03)

Notes: HR (95% CI) and P-values are reported. A HR less than one means that a patient is less likely to have the investigation compared to the reference group.

a The Ontario marginalization index is a group-level measure of socioeconomic factors, which are used as a proxy for individual-level socioeconomic status. A higher score equates to greater marginalization, and a lower socioeconomic status. Hazard ratios less than one suggest that a patient with a lower socioeconomic status is less likely to have an investigation.

b Lesion data were coded as unknown for 20% (315) of the 1,551 patients.

Abbreviations: ADG, aggregated diagnostic groups; CI, confidence interval; HR, hazard ratio.

Table S1 OHIP fee codes used to define relevant urologic investigations

OHIP fee code	Category	Description
Z606	Cystoscopy	Diagnostic cystoscopy
Z607	Cystoscopy	Repeat cystoscopy within 30 days
G192	Urodynamics	Video fluoroscopic multichannel urodynamic assessment to include monitoring of intravesicular, intra-abdominal, and urethral pressures, with simultaneous fluoroscope imaging and recording of filling and voiding phases including interpretation
G193	Urodynamics	Complete multichannel urodynamic assessment – to include monitoring of intravesicular, intra-abdominal, and urethral pressures, with or without pressure-flow studies
E777	Urodynamics	Cystometrogram (to include urethral pressure profile if necessary)
X409	Renal imaging	Abdominal CT without IV contrast
X410	Renal imaging	Abdominal CT with IV contrast
X126	Renal imaging	Abdominal CT with and without IV contrast
J135	Renal imaging	Abdominal US complete
J435	Renal imaging	Abdominal US complete
J128	Renal imaging	Abdominal US limited study
J428	Renal imaging	Abdominal US limited study
X130	Renal imaging	Intravenous pyelogram

Note: Multiple codes within 72 hours are considered one event.

Abbreviations: CT, computed tomography; IV, intravenous; US, ultrasound; OHIP, Ontario Health Insurance Plan.