Table 7 Comparative psychometric properties of the SPHERE-21 and BDI

Number of items

14 (for anxiety-depression)

21

Short form for clinical use

SPHERE-12 (six items for anxiety-depression)

BDI-11

IRT requirements

Monotonicity verified

Good correlation of items with the latent trait

Monotonicity breached for items 9 and 10

Poor correlation of item 19 with the latent trait [53]

Sex DIF

Limited (DIF < 0.25)

Large DIF for item 14 (DIF = 0.32) Limited otherwise (DIF < 0.25) [53]

Age group DIF

Limited (DIF < 0.25); comparable construct from age 9 to 28 years

Not tested at item level (IRT)

Not investigated in a population sample

Comparable structure and internal consistency (Cronbach’s alpha) for adolescent inpatients [98]

Language(s)

Arabic, Cantonese, Croatian, Dutch, English, Greek, Italian, Japanese, Mandarin, Portuguese, Serbian, Spanish, Turkish, Vietnamese^a

Arabic, Chinese, English, Farsi, Finnish, French, German, Japanese, Korean, Norwegian, Portuguese, Spanish, Swedish, Turkish

Test-retest

0.47 [0.23,0.66] at three months

0.48–0.86 [80] depending on the sample and test-retest interval

Cronbach’s alpha

0.87

0.81 [80, 81]

Heritability

0.41 [0.32,0.49] between ages nine and 12 years, 0.42 [0.33,0.50] at 13 to 14 years, 0.29 [0.20,0.38] at 15 to 16 years and 0.37 [0.21,0.51] between ages 17 and 28 years

(AE models, anxiety-depression scores)

0.18 [0.05,0.31]

(AE model, mean age 31 years, range 16–71) [84]

Association with DSM-IV diagnoses

Significant from age 15 years with alcohol and Marijuana dependence; and from age 13 years for MDD and social anxiety (anxiety-depression subscale).

Not evaluated in general population

Price

Free

Around 2 USD per questionnaire [99]