Table 2

Sensitivity analyses with regard to adjustment for publication bias, presence of low back pain at baseline, age of participants, adjustment for confounding factors and other methodological quality of included studies

CharacteristicModerate versus low activityHigh versus low activityActive versus inactive
No of studiesSampleRR95% CIp ValueNo of studiesSampleRR95% CIp ValueNo of studiesSampleRR95% CIp Value
Low back pain in the past 1–12 months
 Overall1299010.950.87 to 1.041399060.960.80 to 1.152038 3890.980.93 to 1.02
 Adjustment for publication bias120.950.87 to 1.04130.960.80 to 1.15200.980.93 to 1.02
Low back pain status at baseline
 Without1088830.970.86 to 1.091188881.050.89 to 1.241416 7401.030.95 to 1.12
 With or without210180.930.78 to 1.100.46210180.680.45 to 1.020.069621 6490.950.91 to 1.000.12
Age
 Adolescent213771.010.84 to 1.21316420.760.33 to 1.73213771.060.68 to 1.67
 Adult961910.970.86 to 1.09961910.980.84 to 1.141734 8090.980.94 to 1.02
 Elderly (70+)123330.830.67 to 1.030.23120731.030.84 to 1.250.47122030.930.73 to 1.190.52
Confounding
 Unadjusted413520.990.83 to 1.18413520.720.51 to 1.00457350.960.82 to 1.12
 Adjusted885490.940.84 to 1.050.65985541.060.89 to 1.250.0691632 6540.980.93 to 1.030.73
Selection bias
 Low429030.940.81 to 1.09429030.910.59 to 1.42429030.950.76 to 1.12
 Moderate563850.910.81 to 1.02663900.950.79 to 1.16923 2610.960.93 to 0.98
 High36131.371.01 to 1.850.2036131.240.85 to 1.820.49712 2251.020.96 to 1.070.02
Performance bias
 Low627580.990.87 to 1.12730230.860.60 to 1.22627580.970.81 to 1.17
 Moderate671430.920.80 to 1.07668831.040.87 to 1.251330 7250.980.94 to 1.03
 High00.4000.32149060.970.82 to 1.140.83
Attrition bias
 Low647550.990.80 to 1.23644951.210.95 to 1.53758551.080.94 to 1.25
 Moderate651460.950.86 to 1.06651460.850.69 to 1.06716 6240.930.86 to 1.01
 High00.9512650.440.18 to 1.000.02615 9100.990.93 to 1.040.42
Frequent or chronic low back pain
 Overall334 4190.860.79 to 0.94334 4190.700.48 to 1.03950 9150.840.77 to 0.92
 Adjustment for publication bias30.860.79 to 0.9450.840.60 to 1.18120.880.80 to 0.96
 Excluding the largest study (HUNT)51 220020.850.51 to 1.42220020.520.34 to 0.81818 4980.830.74 to 0.94
Low back pain status at baseline
 Without334 4190.860.79 to 0.94334 4190.700.48 to 1.03645 7730.840.77 to 0.91
 With or without00351420.870.68 to 1.110.57
Age
 Adolescent00111060.750.57 to 1.00
 Adult233 0320.860.79 to 0.94233 0320.840.75 to 0.93547 4140.900.83 to 0.98
 Elderly (70+)113870.860.48 to 1.540.99113870.530.34 to 0.840.30323950.730.63 to 0.840.24
Confounding
 Unadjusted113870.860.48 to 1.54113870.530.34 to 0.84323950.730.63 to 0.84
 Adjusted233 0320.860.79 to 0.940.99233 0320.840.75 to 0.930.30648 5200.890.82 to 0.970.05
Selection bias
 Low or moderate233 8040.860.79 to 0.94233 8040.710.45 to 1.09746 5410.830.77 to 0.90
 High16150.830.28 to 2.310.9516150.440.06 to 2.590.72243741.070.88 to 1.300.08
Performance bias
 Low220020.850.51 to 1.42220020.530.34 to 0.82233 1480.790.66 to 0.96
 Moderate132 4170.860.79 to 0.940.98132 4170.840.75 to 0.940.29717 7670.860.76 to 0.970.51
Attrition bias
 Low334 4190.860.79 to 0.94334 4190.700.48 to 1.03541 9430.830.74 to 0.92
 Moderate or high00489720.870.74 to 1.030.49