Background
Methods
Study cohort
All-cause | Colorectal cancer | ||||||
---|---|---|---|---|---|---|---|
sub group | N (%) | deaths (%) | survival [95% CI] | p | deaths (%) | survival [95% CI] | p |
All patients in cohort | 22,727 | 41.1 | 58.1 [57, 58] | 31.8 | 66.3 [66, 67] | ||
Area-Remoteness Index of Australia (ARIA)
|
< 0.001
|
< 0.001
| |||||
Major city | 13,155 (57.9) | 39.6 | 59.6 [59, 60] | 30.0 | 68.1 [68, 69] | ||
Inner regional | 5,139 (22.6) | 41.4 | 57.8 [56, 59] | 32.2 | 65.9 [65, 67] | ||
Outer regional | 3,485 (15.3) | 45.1 | 54.1 [52,56] | 36.0 | 61.6 [60, 63] | ||
Remote1
| 948 (4.2) | 46.2 | 53.1 [50,56] | 38.2 | 59.6 [56, 63] | ||
Index of Relative socioeconomic advantage and disadvantage (IRSAD)
|
< 0.001
|
< 0.001
| |||||
Quintile 5 (least disadvantaged) | 3,193 (14.1) | 36.4 | 62.8 [61, 65] | 28.0 | 70.4 [69, 72] | ||
Quintile 4 | 5,101 (22.4) | 38.9 | 60.2 [59, 62] | 29.8 | 68.3 [67, 70] | ||
Quintile 3 | 6,075 (26.7) | 41.0 | 58.2 [57, 59] | 32.2 | 65.9 [65, 67] | ||
Quintile 2 | 5,335 (23.5) | 44.5 | 54.6 [53,56] | 34.5 | 63.3 [62, 65] | ||
Quintile 1 (most disadvantaged) | 3,023 (13.3) | 43.8 | 55.4 [54,57] | 33.5 | 64.2 [62, 66] | ||
Age group
|
< 0.001
|
< 0.001
| |||||
20 to 49 | 1,873 (8.2) | 32.0 | 67.4 [65, 70] | 29.3 | 69.8 [68, 72] | ||
50 to 59 | 3,938 (17.3) | 32.8 | 66.7 [65, 68] | 29.7 | 69.3 [68, 71] | ||
60 to 69 | 6,578 (28.9) | 37.1 | 62.1 [61, 63] | 30.7 | 67.8 [67, 69] | ||
70 to79 | 7,718 (34.1) | 45.6 | 53.5 [52,55] | 32.4 | 64.8 [64, 66] | ||
80 to 84 | 2,620 (11.5) | 56.7 | 41.9 [40,44] | 37.7 | 58.4 [56, 60] | ||
Gender
|
< 0.001
|
=0.003
| |||||
Male | 12,879 (56.7) | 42.9 | 56.2 [55,57] | 32.5 | 65.1 [64, 66] | ||
Female | 9,848 (43.3) | 38.8 | 60.6 [60, 62] | 30.8 | 67.7 [67, 69] | ||
I
ndigenous status
|
< 0.001
|
< 0.001
| |||||
Non Indigenous | 20,868 (91.8) | 43.1 | 56.1 [55,57] | 33.4 | 64.5 [64, 65] | ||
Indigenous | 181 (0.8) | 45.3 | 53.7 [45, 61] | 35.4 | 63.1 [55, 70] | ||
Not stated | 1,678 (7.4) | 16.7 | 82.9 [81, 85] | 11.3 | 88.3 [87, 90] | ||
Marital status
|
<0.001
|
< 0.001
| |||||
Married | 14,532 (63.9) | 39.0 | 60.1 [59, 61] | 30.8 | 67.4 [67, 68] | ||
Never married/single | 1,541 (6.8) | 46.5 | 52.6 [50,55] | 36.2 | 61.5 [59, 64] | ||
Widowed | 3,951 (17.4) | 48.2 | 51.1 [49,52] | 34.2 | 63.2 [62, 65] | ||
Divorced | 1,822 (8) | 44.4 | 54.7 [52,57] | 36.2 | 61.6 [59, 64] | ||
Separated | 454 (2) | 31.9 | 67.3 [63, 71] | 24.4 | 74.3 [70, 78] | ||
Not stated | 427 (1.9) | 20.6 | 79.3 [75, 83] | 15.5 | 84.2 [80, 87] | ||
Occupation category
|
< 0.001
|
< 0.001
| |||||
Professional | 4,783 (21.1) | 48.6 | 50.6 [49,52] | 39.0 | 58.4 [57, 60] | ||
White collar | 2,665 (11.7) | 52.6 | 46.7 [44,49] | 41.4 | 55.6 [54, 58] | ||
Blue Collar | 3,789 (16.7) | 59.5 | 39.4 [38,41] | 47.0 | 48.9 [47,51] | ||
Not in labor force | 7,529 (33.1) | 33.5 | 65.9 [65, 67] | 25.5 | 73.3 [72, 74] | ||
Not stated/ Inadequately described | 3,961 (17.4) | 21.0 | 78.2 [77, 79] | 14.0 | 85.2 [84, 86] | ||
Country birth
2
|
< 0.001
|
< 0.001
| |||||
Australia | 17,367 (76.4) | 41.9 | 57.2 [57, 58] | 32.3 | 65.7 [65, 66] | ||
Other English-speaking | 4,580 (20.2) | 39.2 | 60.2 [59, 62] | 30.7 | 67.8 [66, 69] | ||
Non-English-speaking | 780 (3.4) | 34.0 | 64.2 [61, 68] | 26.4 | 71.1 [67, 74] | ||
Site
3
|
=0.003
|
< 0.001
| |||||
Proximal(R) colon | 7,874 (34.6) | 41.8 | 57.5 [56, 59] | 31.7 | 66.4 [64, 67] | ||
Distal (L) colon | 5,865 (25.9) | 39.5 | 59.6 [58, 61] | 30.0 | 68.8 [68,70] | ||
Colon NOS | 1,299 (5.7) | 54.0 | 45.3 [43,48] | 44.5 | 53.2 [50,56] | ||
Rectal | 7,689 (33.8) | 39.4 | 59.8 [59, 60] | 31.0 | 66.9 [65, 68] | ||
Stage
|
< 0.001
|
< 0.001
| |||||
Stage A | 4,332 (19.1) | 18.3 | 81.1 [80, 83] | 7.8 | 91.7 [91, 93] | ||
Stage B | 6,323 (27.8) | 28.9 | 70.3 [69, 71] | 18.1 | 80.4 [79, 81] | ||
Stage C | 5,846 (25.7) | 47.9 | 50.8 [50,52] | 39.6 | 57.5 [56, 58] | ||
Stage D | 2,576 (11.3) | 84.7 | 13.9 [12,15] | 80.6 | 15.6 [14,17] | ||
Unknown stage | 3,650 (16.1) | 47.4 | 51.9 [50,54] | 36.9 | 60.9 [59, 62] | ||
Differentiation
|
< 0.001
|
< 0.001
| |||||
Well differentiated | 1,107 (4.9) | 31.9 | 67.3 [65, 70] | 20.1 | 75.9 [76, 81] | ||
Moderate differentiated | 13,953 (61.4) | 36.7 | 62.4 [62, 63] | 27.4 | 70.7 [70, 71] | ||
Poor differentiated | 4,206 (18.5) | 52.9 | 46.2 [45,48] | 44.2 | 53.3 [52,55] | ||
Not stated | 3,461 (15.2) | 47.2 | 52.2 [50,54] | 38.0 | 60.3 [59, 62] | ||
Surgical margins
|
< 0.001
|
< 0.001
| |||||
Clear | 16,664 (73.4) | 36.3 | 62.9 [62, 64] | 26.9 | 71.2 [70, 72] | ||
Positive | 530 (2.3) | 39.8 | 59.7 [55, 61] | 31.1 | 67.3 [63, 71] | ||
Unknown | 5,533 (24.3) | 55.7 | 43.6 [43,45] | 46.4 | 51.2 [50,53] | ||
Distance to Treatment
|
< 0.001
|
< 0.001
| |||||
0-99 km | 16,042 (70.5) | 39.4 | 59.7 [59, 61] | 30.1 | 68.1 [67, 69] | ||
100-399 km | 5,173 (22.8) | 44.9 | 54.4 [53,56] | 35.2 | 62.3 [61, 64] | ||
400 or more km | 1,512 (6.7) | 45.7 | 53.5 [51,54] | 37.8 | 60.3 [58, 62] |
Geocoding and travel distance calculations
Survival data
Extraction of clinical data from pathology forms
Stage at diagnosis
Surgical margins
Geographical area
Area-level socioeconomic disadvantage
Geographic remoteness
Statistical analysis
Discrete-time multilevel logistic survival models
Model comparison
The median odds ratio
The interval odds ratio
Results
Study population
Bivariate Kaplan-Meier survival analysis
Discrete-time multilevel logistic survival analysis
Development of final all-cause survival model
Model | description1
| DIC2
| Area-variance (95% CrI)3
| p value | % reduction variance4
| MOR (95% CrI)5
|
---|---|---|---|---|---|---|
All-cause survival
| ||||||
1 | Null (no explanatory variables) | 57769.71 | 0.025 (0.014, 0.039) | <0.001 | - | 1.16 (1.13, 1.21) |
2 | Individual-level covariates5
| 46072.45 | 0.011 (0.006, 0.018) | 0.042 | 56 | 1.10 (1.08, 1.14) |
3 | Individual-level covariates and area-remoteness | 46058.44 | 0.007 (0.003, 0.014) | 0.101 | 72 | 1.08 (1.05, 1.12) |
4 | Individual-level covariates and area-disadvantage | 46054.03 | 0.006 (0.001, 0.014) | 0.078 | 76 | 1.08 (1.03, 1.12) |
5 | Individual- and both area-level covariates | 46046.57 | 0.005 (0.001, 0.012) | 0.118 | 80 | 1.07 (1.03, 1.11) |
6 | All covariates with area-level interactions | 46051.12 | 0.005 (0.001, 0.012) | 0.128 | 80 | 1.07 (1.03, 1.11) |
Colorectal cancer-specific survival
| ||||||
7 | Null (no explanatory variables) | 48609.89 | 0.021 (0.011, 0.034) | 0.001 | - | 1.15 (1.10, 1.19) |
8 | Individual -level covariates | 37013.72 | 0.008 (0.003, 0.012) | 0.044 | 61 | 1.09 (1.05, 1.11) |
9 | Individual-level covariates and area-remoteness | 36987.44 | 0.003 (0.001, 0.007) | 0.231 | 86 | 1.05 (1.02, 1.08) |
10 | Individual-level covariates and area-disadvantage | 36995.14 | 0.004 (0.001, 0.011) | 0.173 | 81 | 1.06 (1.02, 1.10) |
11 | Individual- and both area-level covariates | 36979.49 | 0.002 (0.001, 0.008) | 0.231 | 91 | 1.04 (1.02, 1.09) |
12 | All covariates with area-level interactions | 36993.31 | 0.003 (0.001, 0.011) | 0.298 | 86 | 1.05 (1.02, 1.10) |
Development of final CRC-specific survival model
Area-level interactions
Area-level variance
Impact of area-level covariates on area-level variation
IOR-801,2
| ||
---|---|---|
All-cause survival
|
Colorectal cancer-specific survival
| |
Model 53
| Model 113
| |
Area-Remoteness Index of Australia (ARIA)
| ||
Major city
|
1.00
|
1.00
|
Inner regional
| 0.89, 1.15 | 0.90, 1.06 |
Outer regional
| 0.96, 1.24 | 1.06, 1.25 |
Remote
4
| 1.01, 1.31 | 1.14, 1.34 |
Index of Relative socioeconomic advantage and disadvantage (IRSAD)
| ||
Quintile 5 (least disadvantaged)
|
1.00
|
1.00
|
Quintile 4
| 1.01, 1.30 | 1.03, 1.21 |
Quintile 3
| 1.04, 1.34 | 1.06, 1.25 |
Quintile 2
| 1.07, 1.39 | 1.11, 1.30 |
Quintile 1 (most disadvantaged)
| 1.10, 1.42 | 1.13, 1.39 |
Fixed parameter estimate
All-cause |
p
| Colorectal cancer-specific |
p
| |
---|---|---|---|---|
sub group | OR (95% CrI)1
| OR (95% CrI)1
| ||
Area-Remoteness Index of Australia (ARIA)
|
=0.004
|
=0.003
| ||
Major city | 1.00 | 1.00 | ||
Inner regional | 0.95 (0.88, 1.02) | 0.98 (0.90, 1.06) | ||
Outer regional | 1.09 (1.01, 1.18) | 1.15 (1.05, 1.25) | ||
Remote2
| 1.15 (1.02, 1.28) | 1.24 (1.07, 1.42) | ||
p-value | ||||
Relative socioeconomic advantage and disadvantage (IRSAD)
|
<0.001
|
<0.001
| ||
Quintile 5 (least disadvantaged) | 1.00 | 1.00 | ||
Quintile 4 | 1.14 (1.03, 1.23) | 1.12 (1.01, 1.23) | ||
Quintile 3 | 1.18 (1.08, 1.29) | 1.15 (1.03, 1.27) | ||
Quintile 2 | 1.22 (1.11, 1.34) | 1.20 (1.07, 1.33) | ||
Quintile 1 (most disadvantaged) | 1.25 (1.10, 1.36) | 1.23 (1.09, 1.30) | ||
Time (years after diagnosis)
| 0.45 (0.41, 0.50) |
<0.001
| 0.47 (0.42, 0.52) |
<0.001
|
Time-squared ([years after diagnosis]squared])
| 1.07 (1.05, 1.08) |
<0.001
| 1.04 (1.02, 1.07) |
<0.001
|
Age group
|
<0.001
|
<0.001
| ||
20 to 49 | 0.24 (0.21, 0.27) | 0.37 (0.33, 0.43) | ||
50 to 59 | 0.29 (0.26, 0.32) | 0.45 (0.41, 0.51) | ||
60 to 69 | 0.42 (0.39, 0.46) | 0.59 (0.54, 0.65) | ||
70 to79 | 0.68 (0.63, 0.73) | 0.77 (0.70, 0.84) | ||
80 to 85 | 1.00 | 1.00 | ||
Gender
|
<0.001
|
<0.001
| ||
Male | 1.00 | 1.00 | ||
Female | 1.08 (1.02, 1.14) | 1.17 (1.10, 1.25) | ||
Marital status
|
<0.001
|
<0.001
| ||
Married | 1.00 | 1.00 | ||
Never married/ single | 1.33 (1.21, 1.46) | 1.29 (1.16, 1.43) | ||
Widowed | 1.11 (1.03, 1.19) | 1.06 (0.97, 1.14) | ||
Divorced | 1.18 (1.08, 1.29) | 1.17 (1.06, 1.29) | ||
Separated | 0.94 (0.77, 1.13) | 0.89 (0.71, 1.09) | ||
Not stated | 1.32 (1.02, 1.68) | 1.41 (1.03, 1.85) | ||
Occupation category
|
<0.001
|
<0.001
| ||
Professional | 1.00 | 1.00 | ||
White collar | 1.11 (1.02, 1.20) | 1.07 (0.97, 1.17) | ||
Blue collar | 1.38 (1.29, 1.49) | 1.36 (1.25, 1.47) | ||
Not in labor force | 0.46 (0.43, 0.50) | 0.50 (0.46, 0.54) | ||
Not stated/ Inadequately described | 0.35 (0.32, 0.39) | 0.34 (0.31, 0.38) | ||
Country birth
3
|
=0.045
|
=0.040
| ||
Australia | 1.00 | 1.00 | ||
Other english-speaking | 0.96 (0.90, 1.02) | 0.99 (0.92, 1.06) | ||
Non-english-speaking | 0.88 (0.76, 0.97) | 0.87 (0.74, 0.86) | ||
Indigenous status
|
<0.001
|
<0.001
| ||
Non indigenous | 1.00 | 1.00 | ||
Indigenous | 1.16 (0.89, 1.49) | 1.09 (0.99, 1.44) | ||
Not stated | 0.45 (0.39, 0.51) | 0.43 (0.36, 0.50) | ||
Site
4
|
=0.076
|
=0.134
| ||
Proximal (R) colon | 1.02 (1.01, 1.08) | 1.01 (0.99, 1.13) | ||
Distal (L) colon | 1.03 (0.96, 1.10) | 0.97 (0.93, 1.00) | ||
Colon NOS | 1.04 (1.01, 1.16) | 1.02 (0.99, 1.07) | ||
Rectal | 1.00 | 1.00 | ||
Stage
|
<0.001
|
<0.001
| ||
Stage A | 1.00 | 1.00 | ||
Stage B | 1.61 (1.47, 1.77) | 2.44 (2.15, 2.77) | ||
Stage C | 3.17 (2.91, 3.45) | 6.09 (5.40, 6.85) | ||
Stage D | 11.41 (10.30, 12.57) | 23.25 (20.39, 26.43) | ||
Unknown stage | 2.09 (1.86, 2.34) | 3.59 (3.09, 4.14) | ||
Differentiation
|
<0.001
|
<0.001
| ||
Well differentiated | 1.00 | 1.00 | ||
Moderate differentiated | 1.14 (1.01, 1.29) | 1.37 (1.18, 1.60) | ||
Poor differentiated | 1.64 (1.44, 1.87) | 2.07 (1.77, 2.43) | ||
Not stated differentiation | 1.25 (1.09, 1.43) | 1.46 (1.24, 1.73) | ||
Surgical margins
|
<0.001
|
<0.001
| ||
Clear | 1.00 | 1.00 | ||
Positive | 1.42 (1.19, 1.66) | 1.55 (1.27, 1.85) | ||
Unknown margin | 1.84 (1.68, 2.01) | 1.97 (1.79, 2.17) |