Table 2

Multivariate generalized estimating equations (GEE) model to assess the effect of high HbF response on QOL. The effect of independent variables (rows) on each outcome measure (columns) at 6, 12, 18 and 24 months during randomized treatment to hydroxyurea or placebo is shown. The dependent variables are: SF-36 Health Status Survey variables (as a percent scores), Mood Profile, Ladder of Life.
Independent Variables
 quality of life Outcome Variables (each column is one model per outcome)

General Health Now
 Physical Functioning
 Social Functioning
 Role-Physical
 Role-Mental
 Mental Health
 Energy-Fatigue
High Response
 0.0008
 NS*
 0.007
 NS
 NS
 NS
 NS
Baseline QOL Value
 <0.0001
 < 0.0001
 < 0.0001
 < 0.0001
 < 0.0001
 < 0.0001
 < 0.0001
Baseline Daily Pain 0–3, 4–6, 7–9
 <0.0001
 NS
 <0.0001
 <0.0001
 0.008
 0.002
 0.002
Baseline Fetal Hemoglobin <0. 5 vs > 0. 5
 NS
 NS
 NS
 NS
 NS
 NS
 NS
Baseline Annual Crisis Rate <6 vs ≥ 6
 0.002
 NS
 NS
 0.0005
 NS
 NS
 NS

Pain Recall (4-week)
 General Health Perception
 Tension-Anxiety
 Depression-Dejection
 Vigor
 Fatigue
 Ladder of Life
High Response
 0.0006
 0.002
 NS
 NS
 NS
 NS
 NS
Baseline QOL Value
 < 0.0001
 < 0.0001
 < 0.0001
 < 0.0001
 <0.0001
 <0.0001
 < 0.0001
Baseline Daily Pain 0–3, 4–6, 7–9
 < 0.0001
 NS
 0.001
 <0.0001
 NS
 0.0004
 0.007
Baseline Fetal Hemoglobin <0. 5 vs > 0. 5
 NS
 NS
 NS
 NS
 NS
 NS
 NS
Baseline Annual Crisis Rate <6 vs ≥ 6
 <0.0001
 0.003
 NS
 NS
 0.004
 NS
 0.008

* NS = p > .01

Ballas et al. Health and Quality of Life Outcomes 2006 4:59   doi:10.1186/1477-7525-4-59