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Table 3 Predictors for being in the best tertile of GHP scores

From: Subcutaneous immunoglobulin in primary immunodeficiency – impact of training and infusion characteristics on patient-reported outcomes

Predictor

Category

Logistic regression

Linear regression

OR

95% CI

p-value

Coefficient

95% CI

p-value

Age

0–17 years

1

 

0.006

0

 

0.004

≥18 years

0.30

0.12, 0.70

−0.52

−0.88, −0.16

Experience with IgG prior to SCIG

Ig-naïve

1

 

0.01

   

Ig-experienced

2.36

1.22, 4.54

Time on treatment

< 2 years

   

0

 

0.06

≥2 years

0.27

−0.01, −0.54

Confidence after traininga

1–5

1

 

0.03

   

6–7

2.18

1.07, 4.44

Number of sites

1–3

1

 

0.01

0

 

0.04

≥4

0.44

0.24, 0.84

−0.24

−0.47, −0.02

TSQM effectiveness scoreb

T2 + T3, ≤75

1

 

0.001

0.13

0.07, 0.18

< 0.001

T1, ≥76 (best)

2.73

1.50, 4.80

PROMIS Fatiguec

T2 + T3, ≥54

1

 

< 0.001

−0.33

−0.39, −0.26

< 0.001

T1, ≤53 (best)

8.26

4.56, 15.0

  1. Multivariate logistic regression and linear regression models calculated predictors for being in the best tertile of GHP scores. GHP was measured on an anchored numeric 1–7 scale (1 = poor health and 7 = excellent health), where respondents were grouped in T2 + T3 (intermediate/worst) if they had a score of ≤ 5 and in T1 (best) if they scored 6 or 7. PROMIS Fatigue T-scores are obtained from published raw score to T-score concordance tables of the PROMIS Fatigue Short Form 7a. With 5 levels on each of the 7 items, the raw scores vary from 7 to 35 and are converted to corresponding T-scores in the range of 29.4 (least fatigue) to 83.2 (most fatigue). TSQM transformed scores (T-scores) were measured on a 0–100 scale (0 = worst satisfaction and 100 = perfect satisfaction)
  2. CI confidence interval, GHP general health perception, IgG immunoglobulin G, OR odds ratio, PROMIS Patient-Reported Outcome Management Information System, SCIG subcutaneous immunoglobulin, SD standard deviation, TSQM Treatment Satisfaction Questionnaire for Medication
  3. aPredictor on an anchored numeric scale from 1 to 7 (1 = not very confident and 7 = very confident). The logistic regression yields an OR which predicts the likelihood of each category achieving the desired best tertile, and a significant OR > 1 implies higher odds than with the reference category. The least squares regression models score on a continuous linear scale using the original 1–7 scale, where a higher coefficient implies a higher GHP
  4. bRegression coefficient reported for a 0.5 SD increase in score (equivalent to 10 units)
  5. cRegression coefficient reported for a 0.5 SD increase in score (equivalent to 5 units). The model had an R2 = 36.2%, suggesting that over a third of scores can be explained by the factors in the final model