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Table 2 Summary of exploratory factor analysis item factor loadingsa of PHQ-9 and R-SMS-DS scores at 3 months follow-up

From: Validity of single item responses to short message service texts to monitor depression: an mHealth sub-study of the UK ACUDep trial

  Group 1 Group 2 Group 3
N = 602 patients with PHQ-9 N = 337 patients with PHQ-9 & R-SMS-DS (any time) N = 213 patients with PHQ-9 & R-SMS-DS (within 6 days)
Loadings Loadings Loadings
One-Factor Affective Somatic One-Factor Affective Somatic One-Factor Affective Somatic
PHQ-9 Item Descriptive/Variance explained 64 % --- 73 % --- 61 % --- 69 % --- 61 % --- 70 % ---
1. Loss of interest (anhedonia) .852 .632 - .855 .540 - .854 .448 .453
2. Depressed mood .856 .875 - .876 .768 - .882 .683 -
3. Sleep disturbance .778 - .942 .761 - .973 .740 - .994
4. Fatigue .794 - 1.078 .794 - 1.041 .779 - .831
5. Appetite changes .718 - .640 .700 - .617 .719 - .573
6. Feeling bad about oneself .816 .972 - .840 1.244 - .846 1.169 -
7. Concentration difficulties .791 .554 - .738 .411 - .746 - .634
8. Psychomotor disturbance .735 .507 - .690 .405 - .700 - .714
9. Thoughts of death or self-harm .704 .894 - .724 .860 - .719 .826 -
R-SMS-DS: ‘How depressed have you felt?’ n/ab n/ab n/ab .656 .501 - .692 .616 -
Correlation between factors   --- .834 ---   --- .820 ---   ---.793 ---
  1. aLoadings < 0.400 suppressed
  2. bGroup 1 analyses excluded the SMS score, as this was not available for all patients