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Table 1 Summary of the results of combined models for pre- and post- highly active antiretroviral therapy (HAART) CD4 cell count data, after square root transformation, for patients from the UK Register of HIV Seroconverters dataset

From: Combined models for pre- and post-treatment longitudinal biomarker data: an application to CD4 counts in HIV-patients

  M o d e l 1 M o d e l 2 M o d e l 3 M o d e l 4 M o d e l 5 M o d e l 6
β 0 22.44 (22.13 to 22.74) 22.45 (22.16 to 22.74) 22.44 (22.15 to 22.73) 22.26 (21.96 to 22.56) 22.26 (21.96 to 22.56) 22.23 (21.94 to 22.53)
β 1 −1.36 (−1.52 to −1.2) −1.39 (−1.55 to −1.23) −1.39 (−1.55 to −1.23) −1.3 (−1.46 to −1.14) −1.32 (−1.47 to −1.16) −1.36 (−1.5 to −1.21)
U 00 12.37 (10.64 to 14.37) 13.39 (11.77 to 15.23) 13.42 (11.79 to 15.28) 14.43 (12.68 to 16.43) 14.53 (12.77 to 16.54) 12.92 (11.29 to 14.8)
ρ −0.65 (−0.79 to −0.44) −0.86 (−0.99 to 0.18) −0.84 (−0.98 to −0.1) −0.95 (−1 to 1) −0.92 (−1 to 0.91) −0.63 (−0.76 to −0.44)
U 11 0.55 (0.33 to 0.93) 0.25 (0.08 to 0.75) 0.28 (0.1 to 0.75) 0.2 (0.05 to 0.74) 0.21 (0.06 to 0.74) 0.49 (0.31 to 0.77)
κ pre 9.68 (8.77 to 10.68) 5.91 (5.23 to 6.67) 5.9 (5.22 to 6.68) 5.99 (5.29 to 6.8) 5.92 (5.21 to 6.72) 5.37 (4.37 to 6.6)
H pre 0.11 (0.09 to 0.14) 0.3 (0.25 to 0.37) 0.3 (0.24 to 0.36) 0.31 (0.25 to 0.37) 0.31 (0.25 to 0.38) 0.16 (0.13 to 0.19)
σ 1.25 (1.09 to 1.42) 1.95 (1.89 to 2.01) 1.94 (1.87 to 2) 1.92 (1.85 to 1.99) 1.92 (1.86 to 1.99) 1.32 (1.19 to 1.46)
ϕ1 model:  
long-term Constant for all patients Linear for all patients NCS for all patients Linear for all patients Linear for early treatment Linear for all patients
maximum     stratified by ART t groups or NCS for late stratified by ART t
      treatment group  
At11 7.04 (4.75 to 9.33) 7.06 (4.77 to 9.35) 8.44 (6.05 to 10.83)
At12 0.9 (0.79 to 1.01) 0.9 (0.79 to 1) 0.84 (0.72 to 0.95)
At21 10.73 (7.93 to 13.53) 10.68 (7.85 to 13.51) 12.32 (9.28 to 15.35)
At22 0.67 (0.54 to 0.81) 0.67 (0.53 to 0.81) 0.64 (0.47 to 0.8)
A 1 25.93 (25.49 to 26.36) 11.42 (9.74 to 13.09) 5.1 (0.3 to 9.9) 14.58 (12.3 to 16.86) 3.76 (−1.99 to 9.51) 14.35 (12.32 to 16.38)
A 2 0.69 (0.62 to 0.77) 1.14 (0.84 to 1.44) 0.55 (0.44 to 0.66) 1.23 (0.86 to 1.6) 0.57 (0.46 to 0.67)
A 3 -0.43 (−0.64 to −0.22) −0.32 (−0.63 to −0.01)
A 4 0.82 (0.43 to 1.2) 0.52 (−0.07 to 1.11)
ϕ2 model:  
recovery Constant for all patients Linear for all patients NCS for all patients Linear for all patients Linear for early treatment Linear for all patients
speed     stratified by ART t groups or NCS for late stratified by ART t
      treatment group  
Bt11 2.66 (0.52 to 4.79) 2.8 (0.76 to 4.84) 5.68 (2.94 to 8.43)
Bt12 0.02 (−0.08 to 0.11) 0.01 (−0.08 to 0.1) −0.14 (−0.29 to −1.98e-03)
Bt21 −0.99 (−3 to 1.02) −0.92 (−2.97 to 1.13) 0.23 (−1.39 to 1.86)
Bt22 0.15 (0.05 to 0.26) 0.15 (0.04 to 0.26) 0.01 (−0.1 to 0.12)
B 1 -0.16 (−0.3 to −0.02) −3.34 (−4.19 to −2.48) 1.82 (−0.23 to 3.87) −3.64 (−4.7 to −2.59) 2.42 (0.26 to 4.58) −2.25 (−3.3 to −1.21)
B 2 0.24 (0.2 to 0.28) −0.11 (−0.24 to 0.02) 0.23 (0.17 to 0.29) −0.15 (−0.29 to −0.02) 0.13 (0.07 to 0.19)
B 3 0.28 (0.19 to 0.38) 0.19 (0.04 to 0.33)
B 4 −0.52 (−0.71 to −0.33) −0.28 (−0.58 to 0.02)
P 11.09 (8.76 to 14.03) 2.97 (2.09 to 4.23) 3.05 (2.13 to 4.38) 3.07 (2.19 to 4.31) 3.31 (2.39 to 4.59) 2.72 (1.71 to 4.31)
κ post 7.59 (6.79 to 8.49) 3.09 (2.46 to 3.89) 3.17 (2.53 to 3.98) 3.36 (2.7 to 4.18) 3.3 (2.66 to 4.11) 4.33 (3.5 to 5.36)
H post 0.08 (0.07 to 0.1) 0.42 (0.32 to 0.52) 0.4 (0.3 to 0.5) 0.38 (0.29 to 0.48) 0.39 (0.3 to 0.5) 0.13 (0.11 to 0.16)
Differences in variability  
between patients No No No No No Yes
d f pre 3.84 (3.06 to 4.82)
d f post 4.28 (3.4 to 5.38)
ρ Moran 0.37 (0.19 to 0.52)
n pars 13 15 19 23 27 26
−31954.8 −31724.6 −31708.9 −31664.5 −31656.5 −31299.7a
BIC 64032.85 63591.41 63597.94 63547.06 63568.98 62845.9 a
  1. Parameter estimates are given with 95% confidence intervals in parentheses. aNot comparable to other values in Table, as calculated using Laplace approximation. ART t , time from seroconversion to treatment initiation; BIC, Bayesian information criterion; , log-likelihood; NCS, natural cubic spline; n pars , number of parameters estimated in model The interpretation of each model parameter is listed in Table 2