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Centre for Evidence-
Based Medicine

Completed Prognosis Worksheet for Evidence-Based General Surgery

Citation

Farmakis N, Tudor RG & Keighley MRB. The 5-year history of complicated diverticular disease. Ann Surg Oncol 1998;5:265-70

Are the results of this prognosis study valid?

  1. Was a defined representative sample of patients assembled at a common (usually early) point in the course of their disease?
    Yes. All patients were studied from the time of first emergency admission for complications of diverticular disease.
  2. Was patient follow-up sufficiently long and complete?
    Only 120 of 176 (68%) cases were successfully traced, and follow-up was a minimum of 5 years, by which time 1/3 of the patients had died. The median follow-up was not recorded.
  3. Were objective outcome criteria applied in a "blind" fashion?
    Questionnaires were sent to the GPs of all patients with an index emergency admission, asking about recurrent admissions, symptoms, operations, deaths and cause of death.
  4. If subgroups with different prognoses were identified, was there adjustment for important prognostic factors?
    Subgroups were not identified.
  5. Was there validation in an independent group (test set) of patients?
    No.

Are the valid results of this prognosis study important?

  1. How likely are the outcomes over time?
    Death from diverticular disease: 1.7% per year. Further serious complications: 6.5% per year. Readmission with further complications: 2.5% per year*. Continuing symptoms at 5 years: 33%.
  2. How precise are the prognostic estimates?
    95% Confidence intervals are: for death, 0 - 3.9% per year. For further serious complications, 2.1 - 10.9% per year. For readmission 0 - 5.3% per year. For continuing symptoms at 5 years: 24.6 - 41.4%

Can you apply this valid, important evidence to the management of your patient?

  1. Were the study patients similar to your own?
    As far as we can see, yes.
  2. Will this evidence make a clinically important impact on what you offer to or tell your patient?
    Yes

Additional Notes

  1. The 77 patients in this cohort who had emergency colectomy had a very low risk of further complications (2/77), whereas 37 of the 43 who had conservative treatment had further severe complications.
  2. No data is given about the mortality of emergency colectomy in this group. In the contemporary study of Sarin and Boulos (Ann. Roy. Coll. Surg. Eng. 1994; 76: 117-20.) this was 12%. This paper quotes a similar rate of re-admission (2% per year), and agrees that those who had a colectomy are at very low risk for recurrent problems.
  3. The incomplete follow-up and multi-centre nature of the study suggest possible sources of selection bias.

Clinical Bottom Line

There is a significant risk of further severe complications in patients similar to mine. There is therefore a case for elective prophylactic resection, and some indirect evidence that it is likely to be effective: it is also likely to carry a significant mortality rate. An RCT is needed to determine the balance of risks and benefits in a defined patient group.

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