Table 1

Subgroup analyses

Strata of analysis for each outcome

Number of studies included

HR/RR as appropriate (95% CI); P-value

Heterogeneity


A. Methological quality scores

    Mortality

Studies with a score of ≥6 points [6,7,9,24,52,55,56,58]

8

1.43 (1.26 to 1.63); P <0.001

I2 = 12.4%; P = 0.33

Studies with a score of 5 points [50,51]

2

2.20 (0.77 to 6.34); P = 0.14

I2 = 52.6%; P = 0.15

Studies with a score of <5 points [19-21,53,54,57,59,60]

8

1.48 (1.05 to 2.08); P = 0.03

I2 = 55.5%; P = 0.03

    Time-to-disease progression

Study with a score of ≥6 points [52]

1

1.52 (1.04 to 2.23); P <0.05

Studies with a score of 5 points [50,51]

2

1.91 (0.64 to 5.70); P = 0.25

I2 = 77.4%; P = 0.04

Studies with a score of <5 points [19,21,53]

3

1.90 (0.81 to 4.46); P = 0.14

I2 = 54.9%; P = 0.11

    Lymph node metatasis

Study with a score of ≥6 points [6,7,9,55,56,58]

6

1.21 (0.97 to 1.51); P = 0.09

I2 = 68.5%; P = 0.007

Studies with a score of <5 points [8,11,54,57,60-66]

11

1.47 (1.25 to 1.73); P <0.001

I2 = 38.5%; P = 0.09

    Distant metastasis

Studies with a score of ≥6 points [9,52,55,58]

4

1.81 (1.28 to 2.57); P = 0.001

I2 = 0.0%; P = 0.99

Studies with a score of <5 points [8,11,54,57,61]

5

1.68 (1.08 to 2.62); P = 0.02

I2 = 0.0%; P = 0.74

B. Adjusted versus unadjusted results for Mortality

Studies with results from multivariable analysis [6,7,9,24,51,52,54-56,58]

10

1.44 (1.28 to 1.62); P <0.001

I2 = 21.7%; P = 0.24

Studies without results from multivariable analysis [19-21,50,53,57,59,60]

8

1.48 (0.97 to 2.26); P = 0.07

I2 = 55.3%; P = 0.03


Note: Time-to-disease progression is defined by the occurrence of the outcomes time-to-mortality, recurrence or metastasis.

Tan et al. BMC Medicine 2013 11:52   doi:10.1186/1741-7015-11-52

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