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