Impact of travel time and rurality on presentation and outcomes of symptomatic colorectal cancer: a cross-sectional cohort study in primary care

Peninah Murage; Peter Murchie; Max Bachmann; Michael Crawford; Andy Jones

doi:10.3399/bjgp17X691349

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Figure 1.
Differences in association between rural and urban areas, with and without interaction terms. 1a–4a show differences in association between rural and urban areas (from Table 2, models 1d–4d). The lines show modelled association between travel time and alarm symptoms (1a), emergency admission (2a), Dukes’ stage (3a), and 3-year survival (4a). 1b–4b show the difference in the rural versus urban slope, along with 95% CIs. These differences are statistically significant where the CIs do not cross the zero line.

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Table 1.

Sample characteristics and outcome variables

Variable	Frequency, n (%)	Mean travel time, minutes
Sex
Male	521 (56.3)	8.8
Female	405 (43.7)	7.1

Age, years
<59	157 (17.0)	8.8
60–69	240 (25.9)	7.6
70–79	347 (37.5)	8.5
>80	182 (19.7)	7.1

Location
Rural	298 (32.2)	12.0
Urban	628 (67.8)	6.2

Travel time to GPs, percentile
25^th	232 (25)	2.8
50^th	463 (50)	5.5
75^th	695 (75)	10.3
99^th	917 (99)	43.8

Deprivation
Least deprived Q1	191 (20.6)	8.6
Q2	191 (20.6)	7.8
Q3	171 (18.5)	9.1
Q4	188 (20.3)	8.1
Most deprived Q5	185 (20.0)	6.5

Comorbidities
0	441 (47.6)	7.8
1–2	312 (33.7)	8.3
>3	173 (18.7)	8.3

Symptoms
1–3	825 (89.1)	7.7
>4	101 (10.9)	10.7

Alarm symptoms	373 (40.3)	7.9

Emergency admissions	243 (26.2)	7.7

Dukes’ stage CD	424 (48.9)^a	7.9

↵a Information on disease stage was missing in 58 patients.

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Table 2.

Association between rurality, travel times to the GP, alarm symptoms, and primary outcomes

Explanatory variables	1) Alarm symptoms OR (95% CI)	2) Emergency admission OR (95% CI)	3) Dukes’ stages OR (95% CI)	4) Death within 3 years HR (95% CI)
	Outcome variables without interaction terms
a) Travel time to GP	0.98 (0.84 to 1.14)	0.91 (0.75 to 1.09)	0.91 (0.78 to 1.07)	0.81^a (0.72 to 0.92)
b) Rural	1.08 (0.80 to 1.46)	0.83 (0.58 to 1.18)	0.99 (0.72 to 1.34)	0.71^a (0.57 to 0.88)
c) Alarm symptoms	N/A	0.36^b (0.25 to 0.53)	0.85 (0.64 to 1.14)	1.15 (0.94 to 1.41)

	Outcome variables with interaction terms fitted
d) Travel time to GP	1.34 (0.98 to 1.82)	0.62^b (0.39 to 0.97)	0.94 (0.68 to 1.29)	0.75^b (0.59 to 0.96)
Rural	1.62^b (1.05 to 2.48)	0.61 (0.36 to 1.02)	1.11 (0.72 to 1.70)	0.69^b (0.51 to 0.94)
Travel time/rurality interaction	0.62^b (0.43 to 0.90)	1.69^b (1.02 to 2.79)	0.95 (0.65 to 1.38)	1.18 (0.88 to 1.57)
Alarm symptoms	N/A	0.37^a (0.26 to 0.54)	0.84 (0.63 to 1.12)	1.17 (0.95 to 1.43)
Age, years	1.00 (0.98 to 1.01)	1.02^b (1.00 to 1.03)	0.97^a (0.96 to 0.99)	1.03^a (1.02 to 1.04)
Female	0.95 (0.72 to 1.23)	0.89 (0.63 to 1.24)	0.76 (0.57 to 1.01)	0.74^a (0.60 to 0.90)
Index of deprivation (Carstairs)	0.99 (0.94 to 1.04)	0.99 (0.93 to 1.05)	1.05 (0.99 to 1.11)	1.02 (0.99 to 1.06)
0 comorbidities (Charlson score) (reference)	1	1	1	1
1–2 comorbidities (Charlson)	0.53^a (0.39 to 0.71)	4.87^a (3.27 to 7.26)	0.87 (0.63 to 1.19)	1.20 (0.95 to 1.50)
>3 comorbidities (Charlson)	0.29^a (0.20 to 0.44)	7.26^a (4.63 to 11.39)	1.44 (0.97 to 2.14)	2.53^a (1.98 to 3.25)

↵a P<0.01.
↵b P<0.05. Travel time is the predictor in ‘a’, rurality is the predictor in ‘b’, and alarm symptoms is the predictor in ‘c’. Travel times are interacted with rurality in ‘d’. All models are adjusted for age, sex, deprivation, and comorbidity. For brevity, the coefficients for the covariates are only shown in the models with the interaction term (d). HR = hazard ratio. N/A = not applicable. OR = odds ratio.