Table 3 Univariable and multivariable Cox proportional hazards estimates demonstrating hazard of time to clinic return (A) and time to ART initiation (B)

Age (each year)

0.99 (0.98 – 1.01)

0.435

1.02 (1.00 – 1.03)

0.043

Female gender

0.98 (0.73 – 1.32)

0.885

0.94 (0.68 – 1.28)

0.673

Educational attainment (Ref: primary or less)

1.13 (0.84 – 1.54)

0.419

1.00 (0.73 – 1.38)

0.994

Mbarara district resident

1.17 (0.86 – 1.59)

0.323

1.33 (0.96 – 1.85)

0.082

ART-naïve

1.56 (1.10 – 2.21)

0.011

1.48 (1.00 – 2.19)

0.051

CD4 result (each 100 cells)

0.87 (0.75 – 1.01)

0.062

0.80 (0.69 – 0.93)

0.004

Study period

 Control (no message)

REF

--

REF

--

 Intervention (any message)

2.17 (1.53 – 3.09)

<0.001

2.32 (1.53 – 3.51)

<0.001

Study group

 Control (no message)

REF

--

REF

--

 Direct SMS message

2.73 (1.74 – 4.26)

<0.001

3.05 (1.73 – 5.35)

<0.001

 PIN SMS message

1.71 (1.12 – 2.61)

0.013

2.03 (1.20 – 3.45)

0.009

 Coded SMS message

3.98 (2.38 – 6.65)

<0.001

3.28 (1.85 – 5.65)

<0.001

Characteristic

HR (95 %CI)

P-value

AHR (95 %CI)

P-value

Age (each year)

1.00 (0.98 – 1.02)

0.968

1.02 (1.00 – 1.04)

0.067

Female gender

0.99 (0.70 – 1.40)

0.956

1.12 (0.77 – 1.63)

0.543

Educational attainment (Ref: primary or less)

0.78 (0.55 – 1.11)

0.169

0.71 (0.49 – 1.03)

0.073

Mbarara district resident

0.92 (0.65 – 1.32)

0.664

0.98 (0.68 – 1.44)

0.946

CD4 result (each 100 cells)

0.70 (0.59 – 0.83)

<0.001

0.69 (0.58 – 0.82)

<0.001

Study period

 Control (no message)

REF

 Intervention (any message)

2.21 (1.40 – 3.47)

0.001

2.27 (1.38 – 3.72)

0.001

Study group

 Control (no message)

REF

 Direct SMS message

2.24 (1.31 – 3.84)

0.003

2.40 (1.27 – 4.54)

0.007

 PIN SMS message

1.91 (1.11 – 3.27)

0.018

2.36 (1.21 – 4.61)

0.011

 Coded SMS message

3.54 (1.94 – 6.47)

<0.001

3.06 (1.61 – 5.84)

0.001