Table 1 Description of included studies
From: The prevalence and burden of subthreshold generalized anxiety disorder: a systematic review
Source | Setting | Study period | Study design | Sample size (n) | Age range | Assessment of GAD | Definition of subthreshold GAD | Main findings |
|---|---|---|---|---|---|---|---|---|
Angst, 2006 [43] | General population (Switzerland | ZCS) | 1979-1999 | Longitudinal | 591 | 19–41 | Interview (SPIKE) | DSM-III-R diagnosis of GAD with relaxed duration criterion (1 versus 3 months of duration) | - Point prevalence of SUB GAD = 6.2% for 3-month GAD/7.7% for 1-month GAD |
- High levels of distress, social and work impairment & comparable comorbidity rates and suicide attempts in all SUB GAD groups (sign. differences compared to controls, but no sign. differences compared to 6-month GAD) | ||||||||
- Same age of onset, course, and treatment rates in SUB GAD and GAD cases | ||||||||
- 57.5% of treated patients had SUB DSM-III-R GAD & 50% had SUB DSM-IV GAD | ||||||||
Beesdo, 2009 [44] | General population (Germany | GHS) | 1998-1999 | Cross-sectional | 4181 | 18–65 | Interview (CIDI) | Anxious worrying for at least 3 months with at least 2 of the other DSM-IV criteria for GAD | - Higher associations between GAD, also on the SUB level, and medically unexplained pain compared to other anxiety disorders (independent from comorbid depression) |
- Lowest quality of life, greatest disability and health care utilization in the group with both unexplained pain and (SUB) GAD | ||||||||
Bienvenu, 1998 [45] | General population (United States | ECA) | 1993 | Cross-sectional | 1920 | ≥27 | Interview (DIS) | Group 1: DSM-III-R GAD with duration of 1–6 month / Group 2: DSM-III-R GAD of 1–6 month + fewer than 6 associated symptoms | - Lifetime prevalence of SUB GAD = 8% for group 1/12% for group 2 |
- Higher SUB GAD prevalence in women and younger adults | ||||||||
Carter, 2001 [46] | General population (Germany | GHS) | 1998-1999 | Cross-sectional | 4181 | 18–65 | Interview (CIDI) | Persistent worrying for at least 3 months with at least 2 of the other DSM-IV criteria for GAD | - 12-month prevalence of SUB GAD = 2.1% |
- Higher prevalence in women and in older adults | ||||||||
- High levels of distress and impairment in younger and older SUB GAD cases | ||||||||
- Same comorbidity rates in SUB GAD and threshold GAD (commonly occurring: other anxiety disorders, depression, and somatoform disorders) | ||||||||
Grenier, 2011 [47] | Community-dwelling older adults (Canada|ESA) | 2005-2006 | Cross-sectional | 2784 | ≥65 | Interview (ESA-Q) | Symptoms of anxiety, not meeting all symptom criteria of DSM-IV GAD | - 12-month prevalence of SUB GAD = 3.0% |
- Chronic physical health problems, social disability, use of benzodiazepines and comorbid depression not sign. different between SUB GAD and threshold GAD, but sign. higher in SUB GAD than in controls | ||||||||
Heun, 2000 [48] | Older adults (Germany) | 1993-1994 | Cross-sectional | 287 | ≥60 | Interview (CIDI) | DSM-II-R GAD of 6 months, but fewer than 6 associated symptoms | - Lifetime prevalence of SUB GAD = 5.2% |
- Higher SUB GAD prevalence in women | ||||||||
Hoyer, 2002 [49] | Young women, (Germany|DPS) | 1996-1997 | Cross-sectional | 2064 | 18–25 | Interview (ADIS) | Fulfilling 3 out of 4 DSM-IV criteria for GAD | - Point prevalence of SUB GAD = 2.4% |
- 42% of the SUB GAD cases have other comorbid mental disorders | ||||||||
- Sign. reduced psychosocial functioning in SUB GAD cases compared to controls | ||||||||
Kertz, 2011 [50] | Primary care patients (United States) | NR | Cross-sectional | 329 | 22–88 | Interview (PRIME-MD) | GAD symptoms fulfilling DSM-IV criterion A in addition to 1 or 2 of the other GAD criteria | - Point prevalence of SUB GAD = 6% |
- Point prevalence of GAD symptoms = 24% | ||||||||
- SUB GAD as risk factor for threshold GAD | ||||||||
- Sign. poorer physical health, greater stress and sleep difficulty in SUB GAD than in the no worry group; but no sign. differences between GAD, SUB GAD and no worry group on health care utilization and work productivity | ||||||||
Kessler, 2005 [51] | General population (United States|NCS-R) | 2001-2003 | Cross-sectional | 9282 | ≥18 | Interview (CIDI, SCID) | DSM-IV diagnosis of GAD with relaxed duration criterion (1 versus 3 months of duration) | - Point prevalence of SUB GAD = 2.1% for 3-month GAD / 2.6% for 1-month GAD |
- 12-month prevalence of SUB GAD = 3.9% for 3-month GAD / 5.5% for 1-month GAD | ||||||||
- Lifetime prevalence of SUB GAD = 8% for 3-month GAD / 12.7% for 1-month GAD | ||||||||
- Onset, persistence, comorbidity, social and work impairment not greatly different between 1–5 months GAD and over 6 months GAD | ||||||||
- Short SUB GAD episodes typically recur over years | ||||||||
Maier, 2000 [52] | Primary care patients (Cross-cultural|PPGHC) | 1991-1992 | Longitudinal | 5604 | 15–65 | Interview (CIDI) | All ICD-10 GAD symptom criteria, but relaxed time criterion (<1 versus 1–6 months of duration) | - Not sign. smaller psychosocial disability for SUB GAD with 1–6 months (24.3%) and with GAD over 6 month (24.9%), a little smaller in <1 month SUB GAD (17.3%), higher than in those with chronic somatic diseases (19.5%) |
- Higher disability in (SUB) GAD with other comorbid psychiatric syndromes | ||||||||
Olfson, 1996 [53] | Primary care patients (United States|SDDS-PC) | 1994 | Cross-sectional | 1001 | 35–65 | Interview (SCID) | Excessive anxiety for the past 6 months, not meeting full DSM-III-R criteria for GAD | - Point prevalence of SUB GAD = 6.6% |
- Higher prevalence in younger adults | ||||||||
- 48.5% met criteria for another mental disorder | ||||||||
- After adjustment for covariates, no more differences on work, family, social function, and health care utilization in SUB GAD compared to controls | ||||||||
Potvin, 2011 [54] | Community-dwelling older adults (Canada|ESA) | 2005-2006 | Cross-sectional | 2414 | 65–96 | Interview (ESA-Q) | At least 1 essential symptom of a DSM-IV GAD without fulfilling all criteria | - In men, global cognitive impairment is sign. linked to SUB GAD whether depression was comorbid or not |
Rucci, 2003 [55] | Primary care patients (Italy|PPGHC + BS) | 1991-1992 | Cross-sectional | 554 | 15–65 | Interview (CIDI) | 3+ ICD-10 GAD criteria of 1-month duration including apprehension, motor tension, and automatic overactivity | - Point prevalence of SUB GAD = 8.3% |
- Higher SUB GAD prevalence in women | ||||||||
- (SUB) GAD and depression were the most frequent disorders | ||||||||
- SUB GAD as a precursor of threshold GAD | ||||||||
- Poorer health perception and higher psychological distress in SUB GAD than in controls, but no sign. differences in physical disability | ||||||||
Ruscio, 2007 [56] | General population (United States|NCS-R) | 2001-2003 | Cross-sectional | 5692 | ≥18 | Interview (CIDI, SCID) | DSM-IV symptom criteria for GAD, relaxed duration of 1+ months, also non-excessive worry, and only 2+ criterion C symptoms | - 12-month prevalence of SUB GAD = 6.6% |
- Lifetime prevalence of SUB GAD = 13.7% | ||||||||
- Risk of comorbid psychiatric disorders equal for GAD (92.1%) and SUB GAD (86.3%) | ||||||||
- Sign. risk of onset of various comorbid anxiety & mood disorders caused by SUB GAD | ||||||||
Szadoczky, 2004 [57] | Primary care patients (Hungary) | 1998-1999 | Cross-sectional | 1815 | 18–65 | Interview (DIS) | 1 to 5 symptoms of DSM-III-R GAD and duration of less than 6 months | - Point prevalence of SUB GAD = 5.7% |
- 12-month prevalence of SUB GAD = 10.9% | ||||||||
- Higher SUB GAD prevalence in women | ||||||||
Weiller, 1998 [58] | Primary care patients (Europe|PPGHC) | 1991-1992 | Cross-sectional | 1973 | ≤65 | Interview (CIDI) | 4+ symptoms of ICD-10 GAD with 1 automatic arousal symptom, 3–6 months or all ICD-10 criteria, but no automatic arousal symptom or all ICD-10 criteria, but <4 symptoms | - Point prevalence of SUB GAD = 4.1% |
- Sign. poorer overall health status and higher psychosocial disability in SUB GAD patients than in controls, and no differences between GAD and SUB GAD | ||||||||
- Sign. more general practitioner visits for psychological problems in SUB GAD than controls (but no more anxiolytics or antidepressants in adjusted statistics) | ||||||||
- 39% of SUB GAD an 33% of GAD cases were identified as clinical relevant | ||||||||
Wetherell, 2003 [59] | Older adults (United States) | NR | Cross-sectional | 90 | 55–88 | Interview (ADIS) | Anxiety symptoms, not meeting criteria for DSM-IV GAD | - Sign. more sleep disturbance, fatigue, distress/impairment, higher history of psychotherapy, history and current medication use (antidepressants + benzodiazepines) in GAD and SUB GAD than in controls |
- Current psychotropic medication use in 54.5% of SUB GAD (vs. 6.3% in controls) | ||||||||
Wittchen, 2002 [60] | Primary care patients (Germany) | 2000 | Cross-sectional | 17739 | ≥16 | Questionnaire (GAS-Q) | Full DSM-IV GAD, but of 1–6 months of duration | - Point prevalence of SUB GAD = 1.3% |
- Point prevalence of GAD symptoms = 21.7% | ||||||||
- Higher point prevalence in women | ||||||||
- No sign. differences between SUB GAD and GAD on onset, course, and disability |