Table 1
Items of assessment in QUADAS.
| Items | Assessment | Questions |
|---|---|---|
| Q1 | Adequate spectrum composition | Was the spectrum of patient’s representative of the patients who will receive the test in practice? |
| Q2 | Clear description of selection criteria | Were selection criteria clearly described? |
| Q3 | Adequate reference standard | Is the reference standard likely to correctly classify the target condition? |
| Q4 | Absence of disease progression bias | Is the period between reference standard and index test short enough to be reasonably sure that the target condition did not change between the 2 tests? |
| Q5 | Absence of partial verification bias | Did the whole sample or a random selection of the sample, receive verification using a reference standard of diagnosis? |
| Q6 | Absence of differential verification bias | Did patients receive the same reference standard regardless of the index test result? |
| Q7 | Absence of incorporation bias | Was the reference standard independent of the index test (i.e. the index test did not form part of the reference standard)? |
| Q8 | Adequate description of the index test execution | Was the execution of the index test described in sufficient detail to permit replication of the test? |
| Q9 | Adequate description of the reference test execution | Was the execution of the reference standard described in sufficient detail to permit its replication? |
| Q10 | Absence of index test review bias | Were the index test results interpreted without knowledge of the results of the reference standard? |
| Q11 | Absence of reference test review bias | Were the reference standard results interpreted without knowledge of the results of the index test? |
| Q12 | Absence of clinical review bias | Were the same clinical data available when test results were interpreted as would be available when the test is used in practice? |
| Q13 | Report of uninterpretable results | Were uninterpretable/intermediate test results reported? |
| Q14 | Description of withdrawals | Were withdrawals from the study explained? |
Figure 1
Flow Chart of Studies Selection.
Table 2
Assessment of methodological quality using QUADAS (n: 11).
| No. | First Author (Year) | Screening Tool | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Q10 | Q11 | Q13 | Q14 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Yeasmin F (2013) | FOBT | Y | Y | Y | Y | Y | Y | Y | Y | Y | U | Y | N | N |
| 2. | Lohsiriwat (2014) | FOBT | Y | Y | Y | Y | Y | Y | Y | Y | Y | U | U | U | N |
| 3. | Redwood (2014) | FOBT | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | U | Y |
| 4. | Elsafi (2015) | FOBT | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | N |
| 5. | Mario (2015) | FOBT | N | Y | Y | Y | N | N | Y | U | U | Y | N | N | N |
| 6. | Shapiro (2017) | FOBT | Y | Y | Y | U | Y | Y | Y | Y | Y | Y | U | U | Y |
| 7. | Dvorak (2014) | Genetic | Y | Y | Y | U | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 8. | Amiot (2014) | Genetic | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | N |
| 9. | Johnson DH (2016) | Genetic | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | N |
| 10. | Kanth P (2016) | Genetic | Y | Y | Y | Y | Y | Y | Y | Y | Y | U | Y | Y | Y |
| 11. | Xie (2018) | Genetic | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | N |
| % of agreement ‘yes’ | FOBT | 83.3 | 100 | 100 | 83.3 | 83.3 | 83.3 | 100 | 83.3 | 83.3 | 66.7 | 50 | 16.7 | 33.3 | |
| Genetic | 100 | 100 | 100 | 80 | 100 | 100 | 100 | 100 | 100 | 80 | 100 | 100 | 40 |
Table 3
Characteristic and accuracy of selected fecal occult blood test studies.
| No | Author (Year) | Country | Study design | Study population | Index test | Reference test | Sample size | Sensitivity % | Specificity % | PPV % | NPV % | Accuracy % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Shapiro et al. (2017) [29] | USA | Cross-sectional | Asymptomatic patients from clinics, aged 50–75 years. | HS-gFOBT | Not mentioned | 1095 | 7.4 | 98.6 | 23.6 | 86.0* | |
| 2. | Mario et al. (2015) [30] | Brazil | Cross-sectional | Asymptomatic patients, aged ≥ 50 years. | gFOBT & flexible RSS | Colonoscopy | 102 | 30.0 | 92.4 | 30.0* | 5.0* | 86.3* |
| 3. | Elsafi et al. (2015) [31] | Saudi Arabia | Cohort | Asymptomatic patients aged 50–74 years old from 2 hospitals and confirmed CRC patients. | gFOBT | Cases 257 Control 20 | 50.0 | 77.9 | 3.5 | 99.0 | 71.8* | |
| 4. | Lohsiriwat et al. (2014) [32] | Thailand | Case-control | Histologically proven adenocarcinoma of the colon and rectum patients and individuals with normal colonoscopic findings. | FOBT | Colonoscopy | Cases 96 Control 101 | 41.0 | 97.0 | 93.0 | 63.0 | 70.0 |
| 5. | Redwood et al. (2014) [33] | USA | Cross-sectional | Asymptomatic adults aged ≥ 40 years. | gFOBT | Colonoscopy | 304 | 28.5 | 75.7 | 10.6 | 91.3 | 71.4* |
| 6. | Yeasmin et al. (2013) [34] | Bangladesh | Cross-sectional | Patients suspected to have occult bleeding. | gFOBT | Colonoscopy | 110 | 75.0 | 21.6 | 7.0 | 91.7 | 25.5* |
[i] FOBT- Fecal occult blood test.
gFOBT- Guaiac fecal occult blood test.
HG-gFOBT- High-sensitivity guaiac fecal occult blood test.
RSS- Recto sigmoidoscopy.
PPV- Positive Predictive Value.
NPV- Negative Predictive Value.
* indirectly calculated from data.
Table 4
Characteristic and accuracy of genetic testing.
| No | Author (Year) | Country | Study design | Study population | Index Test | Reference Test | Sample size | Sensitivity % | Specificity % | PPV % | NPV % | Accuracy % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Xie (2018) [35] | China | Case control | Patients aged >18 years old with histologically confirmed mCRC. | mSEPT9 | Colonoscopy | 123 Cases 125 Controls | 61.0 | 89.0 | 89* | 62.8* | 73.4* |
| 2. | Johnson (2016) [36] | USA | Case control | Advanced CRC patients. | BMP3 | Histology | 17 Cases 12 Controls | 76.0 | 92.0 | 92.9* | 73.3* | 82.8* |
| 3. | Kanth (2016) [37] | USA | Case control | Asymptomatic patients from 2 medical centers, aged age 45–75. | BRAF | Colonoscopy | 41 Cases 20 Controls | 94.0 | 72.0 | 79.5* | 90.9* | 83.6* |
| 4. | Dvorak (2014) [38] | Australia | Cross-sectional | Colorectal and Papillary thyroid cancer patients. | BRAF | Histology | 352 | 98.6 | 99.1 | 98.6 | 99.1 | 98.9* |
| 5. | Amiot (2014) [39] | France | Case control | Asymptomatic patients from a teaching hospital. | Wif-1 Gene | Colonoscopy | 90 Cases 157 Controls | 33.0 | 99.0 | 96.9* | 70.7* | 74.1* |
[i] PPV- Positive Predictive Value.
NPV- Negative Predictive Value.
* indirectly calculated from data.
Figure 2
Pooled Sensitivity FOBT.
Figure 3
Pooled Specificity FOBT.
Table 5
Summary Statistics for the Diagnostic Accuracy of FOBT.
| Sub-groups | Number of Studies | P-valuea | I2 (%)b | Sensitivity % (95% CI) | Specificity % (95% CI) |
|---|---|---|---|---|---|
| FOBT | 6 | <0.001 | 83.2–98.9 | 31 (25, 38) | 87 (86, 89) |
[i] a P-value for heterogeneity (chi-square) for both sensitivity and specificity analyses.
b I2 statistics for heterogeneity quantification for both sensitivity and specificity analyses.