Table 3.
Absolute regression equations on determinants of net-health-benefit (NHB)
| Determinant | NHB100 | NHB250 | NHB500 | NHB750 | NHB1,000 | NHB2,500 | NHB5,000 | NHB∞ |
|---|---|---|---|---|---|---|---|---|
| Age | −1 (−3;1) | −1 (−2;1) | −1 (−2;1) | 0 (−2;1) | 0 (−2;1) | 0 (−1;1) | 0 (−1;1) | 0 (−1;1) |
| Female | −26 (−55;2) | −15 (−32;2) | −12 (−26;3) | −11 (−25;4) | −10 (−24;4) | −9 (−23;5) | −9 (−22;5) | −8 (−21;6) |
| Diagnosis | ||||||||
| Primary degeneration (vs. spondylolisthesis) | −37 (−4; −71) | −20 (−42;4) | −14 (−34;7) | −14 (−31;4) | −12 (−29;5) | −10 (−26;7) | −9 (−25;8) | −7 (−26;13) |
| Secondary degeneration (vs. primary deg.) | −50 (−86; −14) | −25 (−45; −3) | −17 (−34;2) | −12 (−31;9) | −11 (−30;9) | −9 (−28;11) | −9 (−28;11) | −11 (−27;6) |
| Duration of pain >2 years. | −23 (−52;6) | −16 (−35;3) | −14 (−30;2) | −13 (−29;2) | −13 (−28;3) | −12 (−27;3) | −12 (−27;3) | −12 (−27;3) |
| Smoking | −34 (−61; −6) | −29 (−46; −12) | −28 (−42; −12) | −27 (−41; −12) | −27 (−41; −12) | −26 (−40; −12) | −26 (−40; −12) | −26 (−39; −12) |
| Occupational status | ||||||||
| On sick leave (vs. working) | −123 (−320;60) | −31 (−136;79) | 0 (−87;93) | 9 (−74;99) | 14 (−68;102) | 24 (−56;108) | 27 (−53;111) | 35 (−44;119) |
| Retired due to sickness (vs. working) | 71 (−126;273) | −26 (−146;98) | −58 (−161;41) | −69 (−168;33) | −75 (−171;26) | −84 (−178;13) | −87 (−180;9) | −83 (−175;13) |
| Pension due to age (vs. working) | −103 (−434;241) | −10 (−216;213) | 20 (−164;215) | 31 (−151;219) | 36 (−134;221) | 45 (−131;230) | 48 (−128;232) | 44 (−135;227) |
| Disability/emotional distress | ||||||||
| Severe disability (vs. moderate-intermediate) | −3 (−40;34) | 16 (−7;38) | 20 (0;40) | 21 (2;40) | 22 (3;41) | 24 (4;42) | 24 (5;43) | 24 (5;43) |
| Emotional distress (vs. severe disability) | 31 (−1;59) | 45 (26;52) | 49 (33;65) | 51 (35;56) | 52 (35;67) | 53 (38;68) | 53 (38;68) | 54 (39;69) |
| Surgical technique | ||||||||
| Instrumented posterolateral (vs. non-inst.) | −25 (−67;16) | −16 (−34;3) | −6 (−29;18) | −4 (−27;19) | −3 (−26;20) | −2 (−24;21) | −1 (−23;21) | −1 (−23;21) |
| Circumferential (vs. inst. posterolateral) | 31 (2;60) | 11 (−16;38) | 10 (−6;26) | 9 (−7;24) | 8 (−8;23) | 6 (−9;21) | 6 (−9;21) | 6 (−10;21) |
| Number of vertebral levels fused >1 | −5 (−36;27) | −1 (−21;18) | −0 (−17;16) | 0 (−16;16) | 0 (-15;16) | 1 (-15;16) | 1 (-15;16) | 1 (-14;17) |
| n | 566 | 566 | 566 | 566 | 566 | 566 | 566 | 566 |
| Probability >F | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 |
| R2 | 0.1027 | 0.1256 | 0.1449 | 0.1523 | 0.1559 | 0.1622 | 0.1642 | 0.1660 |
| Adj. R2 | 0.0749 | 0.0985 | 0.1184 | 0.1260 | 0.1298 | 0.1362 | 0.1383 | 0.1402 |
| Root MSE | 163.31 | 100.92 | 87.31 | 84.24 | 83.03 | 81.43 | 81.08 | 80.81 |
Values are regression coefficients (95% bias-corrected, bootstrapped CI) over hypothetical values of decision-makers’ threshold for willingness-to-pay per effect unit (λ in 2004-EUR). NHB = health-effect − (societal costs/λ); hence, the influence of costs decreases with increasing values of λ and NHB∞ is equivalent to the equation of health effects alone. Health effect was reduction of functional disability from pre-operative to 2 years post-operative measured by the Dallas Pain Questionnaire and summarized into a single index value with range [-400;400]. Interaction variables between occupational status and age were included in equations although not listed, thus, the listed variables of occupational status and age are main-effect dummy variables. Significant determinants (P < 0.05) are in italics