Skip to main content

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
  1. Abbreviations: ADIS Anxiety Disorder Interview Schedule, BS Bologna Study, CI Confidence Interval, CIDI Composite International Diagnostic Interview, DIS Diagnostic Interview Schedule for DSM, DPS Dresden Predictor Study, DSM Diagnostic and Statistical Manual of Mental Disorders, ECA Epidemiologic Catchment Area Program, ESA Enquête sur la Santé des Aînés Study, GAD Generalized Anxiety Disorder, GAS-Q Generalized anxiety screening questionnaire, GHS German National Health Interview and Examination Survey, ICD International Statistical Classification of Diseases and Related Health Problems, n Number of Study Participants, NCS-R National Comorbidity Survey Replication, NR Not Reported, PPGHC WHO International Study on Psychological Problems in General Health Care, PRIME-MD Primary Care Evaluation of Mental Disorders Structured Psychiatric Interview, SCAN Schedules for Clinical Assessment in Neuropsychiatry, SCID Structured Clinical Interview for DSM Diagnoses, SDDS-PC Symptom-Driven Diagnostic System for Primary Care, sign significant, SPIKE Structured Psychopathological Interview and Rating of Social Consequences of Psychic Disturbances for Epidemiology, SUB Subthreshold, Subclinical, or Subsyndromal, ZCS Zurich Cohort Study.