Table 6 Parameter estimates using Poisson and NB mixed-effects model.

From: Negative binomial mixed models for analyzing longitudinal CD4 count data

Covariates

Negative binomial mixed-effects model

Poisson mixed-effects model

Estimate

SE

Pr >|t|

95% CI for NB estimate

Estimate

SE

Pr >|t|

Intercept

6.4697

0.04982

< 0.0001

(6.3715, 6.5679)

6.4625

0.04264

< 0.0001

Time in month

0.007824

0.000989

< 0.0001

(0.005875, 0.009774)

0.006564

0.001706

0.0002

Sqrt_Time

− 0.08649

0.009307

< 0.0001

(− 0.1048, − 0.06815)

− 0.06839

0.009830

< 0.0001

ART initiation (post)

0.2301

0.01238

< 0.0001

(0.2058, 0.2543)

0.1947

0.002537

< 0.0001

Baseline BMI category (ref. = normal weight)

Obese

0.4815

0.1113

< 0.0001

(0.2633, 0.6996)

0.4985

0.1147

< 0.0001

Overweight

0.02561

0.04975

0.6067

(− 0.07191, 0.1231)

0.03131

0.05148

0.5431

Underweight

0.005901

0.07927

0.9407

(− 0.1495, 0.1613)

0.01691

0.08264

0.8379

Baseline HIV viral load category (ref. = low VL)

High VL

− 0.2393

0.05157

< 0.0001

(− 0.3404, − 0.1382)

− 0.3074

0.05065

< 0.0001

Medium VL

− 0.1258

0.04587

0.0061

(− 0.2157, − 0.03585)

− 0.1121

0.04686

0.0168

Undetectable

0.1377

0.2901

0.6351

(− 0.4310, 0.7064)

0.1199

0.2978

0.6872

Number of sexual partners (ref. = stable partner)

Many partners

− 0.1560

0.09394

0.0967

(− 0.3402, 0.02811)

− 0.1674

0.09908

0.0911

No partner

− 0.04821

0.04993

0.3343

(− 0.1461, 0.04967)

− 0.05913

0.05164

0.2522

Age group in years (ref. = < 20)

20–29

0.01166

0.03104

0.7072

(− 0.04919, 0.07251)

− 0.00791

0.007830

0.3125

30–39

0.02852

0.03432

0.4060

(− 0.03876, 0.09580)

− 0.01239

0.008474

0.1438

40–49

− 0.00719

0.04545

0.8743

(− 0.09629, 0.08191)

− 0.03422

0.01112

0.0021

50–59

− 0.05694

0.06662

0.3927

(− 0.1875, 0.07365)

− 0.1399

0.01549

< 0.0001

 ≥ 60

0.2082

0.1532

0.1741

(− 0.09205, 0.5084)

− 0.3107

0.03519

< 0.0001

Education attainment (ref. = secondary or high school)

Primary school

− 0.04509

0.09084

0.6196

(− 0.2232, 0.1330)

− 0.03582

0.09263

0.6990

Residence of participant (ref. = urban)

Rural

− 0.00373

0.03947

0.9246

(− 0.08112, 0.07365)

0.01337

0.04038

0.7406

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