Concordance with national guidelines for colorectal cancer care in New South Wales: a population-based patterns of care study

Jane M Young, David C Leong, Katie Armstrong, Dianne O’Connell, Bruce K Armstrong, Allan D Spigelman, Stephen Ackland, Pierre Chapuis, Andrew B Kneebone and Michael J Solomon
Med J Aust 2007; 186 (6): 292-295. || doi: 10.5694/j.1326-5377.2007.tb00903.x
Published online: 19 March 2007


Objective: To investigate predictors of evidence-based surgical care in a population-based sample of patients with newly diagnosed colorectal cancer.

Design, patients and setting: Prospective audit of all new patients with colorectal cancer reported to the New South Wales Central Cancer Registry between 1 February 2000 and 31 January 2001.

Main outcome measures: Concordance with seven guidelines from the 1999 Australian evidence-based guidelines for colorectal cancer; predictors of guideline concordance; the mean proportion of relevant guidelines followed for individual patients.

Results: Questionnaires were received for 3095 patients (91.6%). Between 0 and 100% of relevant guidelines were followed for individual patients (median, 67%). Concordance with individual guidelines varied considerably. Patient age independently predicted non-concordance with guidelines for adjuvant therapy and preoperative radiotherapy. Adjuvant chemotherapy was more likely if a patient with node-positive colon cancer was treated in a metropolitan hospital or by a general surgeon. Surgeons with a high caseload or specialty in colorectal cancer were more likely to perform colonic pouch reconstruction, prescribe thromboembolism or antibiotic prophylaxis, and were less likely to refer patients with high-risk rectal cancer for adjuvant radiotherapy. Bowel preparation was less likely among older patients and in high-caseload hospitals.

Conclusion: Effective strategies to fully implement national colorectal cancer guidelines are needed. In particular, increasing the use of appropriate adjuvant therapy should be a priority, especially among older people.


All new patients with colorectal cancer reported to the NSW Central Cancer Registry between 1 February 2000 and 31 January 2001 were included.6 As each patient was registered, a questionnaire was mailed to their surgeon to obtain clinical information and referral details. Medical and radiation oncologists were then asked to complete a questionnaire about adjuvant therapy.

The questionnaires addressed 23 of 46 recommendations in the NHMRC guidelines.2 Of these, 13 that were supported by Level I (meta-analyses of randomised controlled trials) or Level II (randomised controlled trial) evidence were considered for this study. Where several guidelines related to the same aspect of care, the guideline with the most direct consequences for patient care was selected. For example, two guidelines pertained to thromboembolic prophylaxis; one recommended thromboembolic prophylaxis, and one stated that unfractionated heparin, low molecular weight heparin, and intermittent calf compression are all effective. In this case, only the guideline recommending thromboembolic prophylaxis was included.

Overall, seven guidelines that addressed different aspects of surgical care and had direct implications for patient outcomes were selected for specific study:

For guidelines relating to adjuvant therapy, care was considered concordant if a patient was referred for consideration of chemotherapy or radiotherapy, or declined referral. For other guidelines, care was considered concordant only if the guideline was actually followed.


Surgeons were identified as specialist colorectal surgeons if they were members of the Colorectal Surgical Society of Australia and New Zealand. Other surgeons were considered general surgeons. Surgeon and hospital caseloads were calculated as the number of patients entered into the study who had a surgical procedure, both for any colorectal cancer, and for rectal cancer separately.

Bivariate associations between guideline concordance and the following patient, surgeon and hospital characteristics were assessed: patient age, patient sex, presentation type (screening or symptomatic), admission type (elective or emergency), cancer site, cancer stage (Dukes classification), number of primary tumours (one or more), intent of surgery (curative or palliative), hospital location (metropolitan or rural), colorectal or general surgeon, surgeon caseload, hospital type (principal referral, other public, or private), and hospital caseload.

We conducted logistic regression modelling using generalised estimating equations with an exchangeable correlation matrix to identify independent predictors of concordance with individual recommendations, after accounting for patient clustering by surgeon. Variables with P < 0.25 in bivariate analyses were entered into the model. Hospital and surgeon caseloads and surgical specialty were entered into all full models regardless of bivariate significance. A manual backwards stepwise approach was used to eliminate variables in order of least significance. Only variables that were significant were retained in the final model. All analyses were undertaken using SAS, version 9.1 (SAS Institute Inc, Cary, NC, USA).

For a summary measure of concordance with the recommendations, each guideline was identified as being relevant or irrelevant for each patient based on clinical criteria. The proportion of relevant guidelines followed was calculated for each patient.


Between 1 February 2000 and 31 January 2001, 3443 new cases of colorectal cancer were notified. Of these, 66 patients were ineligible (36 did not have colorectal cancer; 9 were treated outside NSW; 21 had previous colorectal cancer). The treating doctor was unknown for 63 eligible patients (1.9%), precluding mailing of a questionnaire, and no response was received from doctors treating 219 eligible patients (6.5%). Responses were received for 3095 of 3377 eligible patients (91.6%) from 268 surgeons, and included care provided at 129 hospitals. There were no important differences in age, sex or accessibility to health services between patients for whom a questionnaire was or was not completed (data not shown).

Surgery was performed for 2984 patients (96.4% of those with a completed questionnaire) by 251 surgeons. Patient, disease and provider characteristics for these patients are summarised in Box 1. The median colorectal cancer caseloads were 5 for surgeons (range, 1–86; interquartile range [IQR], 2–14) and 12.5 for hospitals (range, 1–156; IQR, 4–35); for rectal cancer only, they were 3 (range, 1–44; IQR, 1–8) and 5 (range, 1–66; IQR, 2–16), respectively.

Seven hospitals that did not admit any patients having surgery were excluded from hospital-level analyses.

Concordance with guidelines

Box 2 presents the results of the logistic regression, including only the significant predictors of concordance.


We found varied uptake of specific management guidelines for colorectal cancer. Almost all patients received antibiotic and DVT prophylaxis, as recommended. For adjuvant therapy and preoperative radiotherapy, about 60% of eligible patients were offered the recommended therapy. Almost 95% of eligible patients received mechanical bowel preparation, despite the lack of support in the guidelines.

We found that older patients were less likely to be offered adjuvant therapy. Suboptimal use of adjuvant therapies has been reported elsewhere, with increasing patient age commonly predicting non-referral.7-10 However, recent data for elderly patients with advanced colorectal cancer treated with chemotherapy indicate no greater toxicity and similar probabilities of benefit as for younger patients.11 Preoperative radiotherapy was also less likely to be given to older patients, regardless of whether surgery was intended to be curative or palliative. Given these results, the development of resources focusing on appropriate care for older patients appears to be a priority.

The only guideline we investigated that related to technical aspects of colorectal cancer surgery was the use of colonic pouch reconstruction. This was also the only guideline where subspecialist training in colorectal surgery was predictive of concordance. Surgical education is an important component of any strategy to improve surgical care. Although the role of subspecialisation in colorectal surgery remains controversial,12 systematic training of surgeons in new, effective techniques can have a major effect on cancer outcomes. In Sweden, for example, training surgeons in total mesorectal excision for rectal cancer led to significant reductions in local recurrence rates and 2-year cancer-related mortality.13,14

We found that patients with node-positive colon cancer were significantly more likely to be offered adjuvant chemotherapy if they were treated by a general surgeon rather than a colorectal surgeon. The reason for this is unclear and warrants further investigation.

The greatest discordance we found related to bowel preparation, which has no support in the guidelines. Moreover, there is evidence that it may increase anastomotic leak rates.15 Lack of familiarity with the evidence may be one reason why the guideline is not followed. A survey of colorectal surgeons just before release of the NHMRC guidelines reported very low awareness of the evidence against bowel preparation.16 Even after dissemination of the national guidelines and publication of further studies on the topic, a survey in 2001 found that knowledge of this evidence had not changed.17 Technical and aesthetic considerations may also influence the readiness of surgeons to follow this guideline. However, surgeon-related factors were not predictive of concordance in our study. The only independently predictive factors were patient age and hospital caseload, highlighting the potential importance of institutional factors in determining guideline compliance.

Despite substantial literature supporting an association between higher caseload (particularly for rectal cancer) and improved care for people undergoing surgery for colorectal cancer,4,18 we found limited evidence of it. Use of antibiotic and DVT prophylaxis did relate to surgeon caseload, but the absolute differences were small. Use of adjuvant radiotherapy for patients with high-risk rectal cancer was lower among surgeons with higher caseloads. It is plausible that this is due to a lower perceived need for adjuvant radiotherapy if surgeons with higher caseloads are using better techniques. We focused only on care processes; patient outcomes such as survival and recurrence rates could vary by caseload. This will be further investigated as follow-up data become available for this cohort.

We calculated the overall proportion of relevant guidelines that were followed for individual patients. Our finding that, on average, 78% of relevant guidelines were followed for individual patients is encouraging. If found to be a robust yet discriminating measure of quality of care, a summary measure such as this could be useful for monitoring the uptake of evidence-based practice over time or between hospitals, while taking into account differences in patient numbers and clinical characteristics.

Strengths of our study include the population-based sample and very high participation rate — data were received for more than 90% of eligible patients. Furthermore, the accuracy of the clinicians’ self-reported data was confirmed in a pilot study, which found good agreement between questionnaire responses and independent medical record audit.6

Our identification of predictors of concordance with individual recommendations provides an empirical base for future strategies to promote uptake of evidence into patient care. In particular, strategies are needed to ensure that all patients who may benefit from adjuvant therapy, including older patients, are fully informed of their treatment options.

2 Independent predictors of concordance with guidelines



Adjusted odds ratio (95% CI)



Colonic pouch reconstruction following resection of low rectal cancer

Surgical intent






4.55 (2.00–10.32)

Surgeon’s specialty

< 0.0001




4.85 (2.30–10.22)

Adjuvant therapy for patients with node-positive colon cancer

Patient’s age

0.93 (0.90–0.95)

< 0.0001


Surgeon’s specialty





1.88 (1.06–3.36)

Hospital location





0.56 (0.32–0.99)

Adjuvant radiotherapy for patients with high-risk rectal cancer

Patient’s age

0.97 (0.95–0.99)



Patient’s sex





1.64 (1.12–2.39)

Surgeon’s caseload

0.99 (0.98–1.00)


Preoperative radiotherapy for patients with fixed or tethered rectal cancer

Patient’s age

0.96 (0.93–0.99)



Surgical intent





4.90 (1.99–12.1)

No routine bowel preparation for elective surgery for colon cancer

Patient’s age

1.01 (1.00–1.03)



Hospital caseload

1.006 (1.003–1.009)

< 0.0001

Antibiotic prophylaxis

Surgeon’s caseload

1.06 (1.01–1.12)



DVT prophylaxis

Surgeon’s caseload

1.08 (1.01–1.15)



* Intracluster correlation coefficient. Change in odds of concordance per increase in patient’s age of 1 year. Change in odds of concordance per increase in caseload of one patient.

  • Jane M Young1,2
  • David C Leong3
  • Katie Armstrong4
  • Dianne O’Connell4,5
  • Bruce K Armstrong6
  • Allan D Spigelman7,8
  • Stephen Ackland9,10
  • Pierre Chapuis11,12
  • Andrew B Kneebone1,12,13
  • Michael J Solomon12

  • 1 Surgical Outcomes Research Centre (SOuRCe), University of Sydney, Sydney, NSW.
  • 2 Sydney South West Area Health Service, Sydney, NSW.
  • 3 John James Medical Centre, Canberra, ACT.
  • 4 Cancer Epidemiology Research Unit, Cancer Council NSW, Sydney, NSW.
  • 5 Faculty of Health, University of Sydney, Sydney, NSW.
  • 6 Sydney Cancer Centre and School of Public Health, University of Sydney, Sydney, NSW.
  • 7 Professorial Surgical Unit, Faculty of Medicine, University of New South Wales, St Vincent’s Hospital Clinical School, Sydney, NSW.
  • 8 Cancer Services, St Vincent’s and Mater Health, Sydney, NSW.
  • 9 Department of Medical Oncology, Newcastle Mater Misericordiae Hospital, Newcastle, NSW.
  • 10 Faculty of Health, University of Newcastle, Hunter Medical Research Institute, Newcastle, NSW.
  • 11 Department of Surgery, Concord Repatriation General Hospital, Sydney, NSW.
  • 12 Discipline of Surgery, University of Sydney, Sydney, NSW.
  • 13 Department of Colorectal Surgery, Royal Prince Alfred Hospital, Sydney, NSW.



This research was supported by a grant-in-aid from MBF Australia and by project grant number 9937291 from the National Health and Medical Research Council. The survey was conducted through and generously supported by The Cancer Council NSW. Bruce Armstrong’s research is supported by a University of Sydney Medical Program Grant. The authors’ work was independent of the funders. We are grateful to specialists who treat colorectal cancer in NSW who generously gave of their time to complete questionnaires for this study.

Competing interests:

None identified.

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