Table 1.
Comparison of study participants with and without schizophrenia.
| Nonpsychiatric comparison group | Schizophrenia group | t or χ2 | df | p | Cohen’s d | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | Mean | SD | N | Mean | SD | |||||
| Sociodemographic variables | ||||||||||
| Age (years) | 140 | 48.7 | 11.2 | 145 | 48.3 | 10.1 | 0.27 | 283 | 0.79 | 0.03 |
| Sex (% female) | 140 | 54 | 145 | 46 | 1.85 | 1 | 0.17 | |||
| Race/ethnicity | 140 | 145 | 4.93 | 2 | 0.09 | |||||
| Non-Hispanic White (%) | 58 | 45 | ||||||||
| Hispanic (%) | 24 | 30 | ||||||||
| Other (%) | 18 | 25 | ||||||||
| Education (years) | 140 | 14.5 | 2.3 | 145 | 12.4 | 2.3 | 8.16 | 283 | <0.001 | 0.97 |
| Cigarette use (packs per day) | 140 | 0.02 | 0.09 | 145 | 0.38 | 0.50 | −8.49 | 283 | <0.001 | −1.01 |
| Psychopathology | ||||||||||
| Antipsychotic daily dose1 | 145 | 1.85 | 1.56 | |||||||
| Duration of illness (years) | 142 | 25.0 | 11.1 | |||||||
| Positive symptoms (SAPS) | 145 | 6.52 | 4.20 | |||||||
| Negative symptoms (SANS) | 145 | 7.21 | 4.35 | |||||||
| Depression (PHQ-9) | 130 | 1.95 | 2.81 | 138 | 7.80 | 6.59 | −9.37 | 266 | <0.001 | −1.16 |
| Perceived stress (PSS) | 130 | 10.9 | 6.04 | 141 | 18.7 | 6.20 | −10.5 | 269 | <0.001 | −1.28 |
| Cognitive performance, quality of life, and everyday functioning | ||||||||||
| Global functioning (TICS-M) | 138 | 37.4 | 4.22 | 141 | 31.0 | 6.02 | 10.2 | 277 | <0.001 | 1.23 |
| Executive functioning (D-KEFS) | 140 | 0.39 | 0.61 | 145 | −0.57 | 0.75 | 11.8 | 283 | <0.001 | 1.40 |
| Quality of life (SF-36) | 131 | 54.7 | 5.83 | 141 | 42.8 | 11.26 | 10.8 | 270 | <0.001 | 1.32 |
| Everyday functioning (UPSA-B) | 140 | 84.2 | 9.9 | 139 | 67.7 | 18.1 | 9.50 | 277 | <0.001 | 1.14 |
| Metabolic measures | ||||||||||
| Body mass index | 139 | 27.6 | 6.64 | 140 | 32.2 | 7.35 | −5.38 | 277 | <0.001 | −0.64 |
| Insulin resistance (HOMA-IR) | 126 | 1.74 | 1.57 | 134 | 3.73 | 5.07 | −4.66 | 258 | <0.001 | −0.58 |
For all measures (except the depression and perceived stress), lower scores suggest worse functioning. D-KEFS, Delis-Kaplan Executive Function System (49, 50); HOMA-IR, Homeostatic Model Assessment of Insulin Resistance (56, 57); PHQ-9, Patient Health Questionnaire-9; measure of depression (43); PSS, Perceived Stress Scale; measure of perceived stress (44); SAPS, Scale for the Assessment of Positive Symptoms; SANS, Scale for the Assessment of Negative Symptoms; SF-36, Medical Outcomes Survey—Short Form 36; measure of mental and physical functioning (61); TICS-M, Telephone Interview for Cognitive Status—Modified (45, 46); UPSA-B, UCSD Performance-Based Assessment-Brief (54, 55).
Antipsychotic medication daily dosages were converted to WHO average daily doses based on published standards (40).