diagnostic accuracy systematic review of rectal bleeding in combination with other symptoms, signs...

Diagnostic accuracy systematic review of rectal bleeding in combination with other symptoms, signs and tests

in relation to colorectal cancer

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Marleen Olde Bekkink

Erasmus student, clinical research fellowDept of General Practice

Radboud University Nijmegen Medical Centre, the Netherlands

8th July 2009

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Background

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*1. Fijten GH et al. 1994 *Mant A. et al. 1988

Incidence of CRC in patients with rectal bleeding

General population: < 1 per 10001 people

General practice: 2-11 per 1001 patients

Secondary care: 36 per 1001 referred patients

1st selection by patient

2nd selection by GP

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Methods - Study protocol

• Inclusion criteria

Population

* Patients recruited from primary care population

* Rectal bleeding and associated symptoms

Study design

* Observational cohort studies

Reference standard and follow up

*Colonoscopy

*Flexible/ rigid sigmoidoscopy (and barium enema)

*Questionnaire/ follow up only

Outcome measures

* Data must allow construction of 2x2 tables

3Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

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Methods – Inclusion of articles

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Potentially relevant citations (n=1534)

Excluded after scanning of citation or abstract (n=1470)

Full text retrieved (n=64)

Excluded (n=56)Reason for exclusion: Setting not in general practice (n = 23) Screening study (n = 5) Case control study (n = 5) Data not extractable from 2x2 table (n = 15) Other (n=8)

Included studies (n=8)

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Methods – Characteristics of the included studies

• No of patients included: 2323

• Prior CRCWeighted average: 7.0 %Median : 8.1 %

Eight included studies (1988 - 2006)

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Included articles: GP settingNo Study ID Prior1 du Troit 2006 5.7% (15/265)2 Ellis 2005 3.4% (11/319)3 Fijten 1995 3.3% (9/269)4 Heintze 2005 4.8% (23/476)5 Mant 1988 11% (16/145)6 Metcalf 1996 8.1% (8/99)7 Norrelund 1996 15.4% (32/208)

14.1% (22/156)8 Wauters 2000 7.0% (27/386)

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Methods – Quality assessment

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

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Methods- Data extraction

• Extraction in 2x2 tables to calculate LR+

Metcalf 1996 prior 8/99

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Sign/ symptom/ characteristics No of patients % population No cancers

Dark red blood loss 31 31% 3

Weight loss 15 15% 2

Blood mixed with stool 46 46% 5

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Results- Pooled positive likelihood ratios

8Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

Patient characteristics No of studies No of patients Pooled PLR (95% CI)

Male 5 1253 1.21 (1.00-1.46)

Age <40y 2 745 0.32 (0.05-2.21)

Age ≥ 60y 6 1760 2.79 (2.00-3.90)

Family history colorectal cancer 3 866 1.05 (0.16-6.88)

Signs/ symptoms No of studies No of patients Pooled PLR (95% CI)

Dark red blood 4 949 1.37 (0.59-3.30)

Weight loss 7 1737 1.89 (1.03-3.07)

Abdominal pain 7 1739 0.94 (0.19-1.59)

Blood mixed with the stool 5 1225 1.91 (0.75-5.51)

Changed bowel habit 5 1254 1.92 (0.54-3.57) Perianal symptoms- pain on defecation 2 411 0.49 (0.25-0.97)

Diagnostic tests No of studies No of patients Pooled PLR (95% CI)

Anaemia (Hb ♀< 12..0 g/dL ♂<13.3 g/dL) 2 700 3.67 (1.30-10.35)

Rectal palpation-haemorrhoid 2 354 0.51 (0.09-2.97)

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Discussion

• Limitations of sub studies

- Reference standard ≠ gold standard

• Limitations of the review

- Internal validity

Reference categories

- External validity

Incidence of colorectal cancer

Edited image (MO) Original: Mayo Foundation for Medical Education and Research

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

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Conclusion

Value of the review

• Implications for clinical practice guidelines

Predictive value of rectal bleeding low-moderate

Alarm symptoms yield only moderate likelihood ratios

• Further studies required calculating independent values

using a multivariable analysis

Olde Bekkink M, McCowan C, Falk G, Teljeur C, Van de Laar F, Fahey T.

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Questions

Thank you!