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Table 4 Summary of Studies with Invalid/Biased Criteria for Confusion

From: The scientific evidence for a potential link between confusion and urinary tract infection in the elderly is still confusing - a systematic literature review

Study Design of Study Patient Sample Number, Age,
Female %, Catheter %
Care Setting Association between Confusion and UTI Primary Aim of Study Confusion Diagnostic Criteria UTI/Bacteriuria Diagnostic Criteria Results
Assantachai et al. 1997 [56] Cross Sectional; Prospective 100 patients with UTI,
Age: ≥ 60 years,
mean 72 +/− 8.6, range 60–100
Female: 78%
Catheter: 46%
Hospital (General and Intensive care wards 95:5) No Confusion
Not stated
Bacteriuria
≥105 bacteria/ml
UTI
Not described
60 out of 100 (60%) patients with UTI had Confusion
Caterino et al. 2012 [59] Cross Sectional; Retrospective 25.4 million presentations of UTI
Age: ≥ 18 years,
18,200,000 aged 18–64, Female 87%
5,015,000 aged 65–84, Female 68%
2,203,000 aged ≥85, Female 76%
Catheter: Unclear
Hospital (Emergency Department) Yes Altered Mental Status
ICD - 9 code 780.97; or documentation of disorientation; or presence of reason for visit ICD - 9 codes 5840.0, 5841.0, or 5842.0
Bacteriuria
Not Stated
UTI
ICD-9 CM codes for UTI; or cystitis; or pyelonephritis;
(590, 595.0, 595.89, 595.9, or 599.0)
Altered mental status was present in 7% of those aged 65–84, and 13% of those aged ≥85, with UTI.
Compared to adults aged 18 to 64 years, those aged ≥85 with UTI were more likely to present with altered mental status. (Adjusted OR = 2.5, 95% CI = 1.3–5.0; p = 0.009)
Nursing home residents more likely to present with altered mental status (Adjusted OR 4.8 95% CI 2.9–7.8 < 0.001)
Gau et al. 2009 [67] Cross-Sectional, case control retrospective 154 bacteriuric patients
Age: ≥65 years, mean 83, SD 8
Female: 84%
Catheter: 51%
Control group
142 non-bacteriuric patients
Age: ≥65 years, mean 82, SD 8
Female: 75%
Catheter: 37%
Hospital Partial Delirium
Defined by delirium, acute confusion, or mental status change as documented on admission
Bacteriuria
≥5 × 104 cfu/ml of a single uropathogen, pyuria, or nitrate positive test results
UTI
Positive urine culture and atleast local symptoms, fever, delirium (mental status change) or other symptoms (lower abdominal pain, falls, emesis)
46 out of 154 (30%) patients with bacteriuria had delirium
Patients with bacteriuria were more likely to have Delirium OR 5.1 (95% CI 2.5–10, P < 0.05)
40 out of 104 (39%) patients with UTI had delirium
Patients with UTI were more likely to have delirium in comparison to patients with asymptomatic bacteriuria. OR 4.6 (95% CI 1.8–12, p < 0.05)
Levkoff et al. 1988 [61] Retrospective Case Controlled 117 Patients with Delirium
Age: ≥60,
54 > 80+
Female: 65%
Catheter: Unclear
Hospital No Delirium
ICD-9 Codes for Delirium
Bacteriuria
Not Stated
UTI
Discharge ICD-9 Codes for UTI
37 out of 117 (32%) with delirium had UTI
UTI was associated with delirium OR 3.05 (95% CI 2.01–4.50)
Lin et al. 2010 [62] Cross-sectional; Retrospective Total 1,968,527 hospitalizations with CHF, UTI, pneumonia or lower limb orthopaedics
Age: ≥ 18 years
1,952,301 without delirium
Age: ≥ 18 years median age 75 female 60%
Catheter: Unclear
16,226 with delirium
Age: median age 83,
Female 63%
Catheter: Unclear
Hospital Partial Delirium
6 ICD-9 Codes
(drug-induced delirium, presenile dementia with delirium, senile dementia with delirium, vascular dementia with delirium, subacute delirium or delirium not otherwise specified)
Bacteriuria
Not Stated
UTI
CMS-DRG classifications kidney/urinary tract infections (DRGs 320–321)
2700 out of 254,000 (1.1%) patients with UTI presented with delirium on admission
3750 out of 254,000 (1.5%) patients with UTI had delirium at any time during hospitalisation
Multivariate models for predicting delirium produced, however UTI used as reference group.
Lin et al. 2010 [63] Cross- Sectional; Retrospective 26,057,988 hospitalizations with CHF, UTI, pneumonia or lower limb orthopaedics
Age: ≥ 18 years
25,806,657 without delirium
Age: ≥ 18 years median age 74 female 60%
Catheter: Unclear
251,331 with any delirium
Age: ≥ 18 years median age 83,
Female 63%
Catheter: Unclear
Hospital Partial Delirium
6 ICD-9 Codes
(drug-induced delirium, presenile dementia with delirium, senile dementia with delirium, vascular dementia with delirium, subacute delirium or delirium not otherwise specified)
Non-dementia, Non-drug Delirium
2 ICD-9 Codes
(subacute delirium or delirium not otherwise specified)
Bacteriuria
Not Stated
UTI
CMS-DRG classifications kidney/urinary tract infections (DRGs 320–321)
58,000 out of 3,158,000 (1.8%) patients with UTI had any delirium
38,000 out of 3,158,000 (1%) patients with UTI had non-dementia, non-drug delirium
Yearly prevalence of any delirium in patients with UTI 16.6–20.9/1000
Multivariate models for predicting delirium produced, however UTI used as reference group
Lixouriotis et al. 2011 [53] Cross-sectional; Retrospective 9 patients with Delirium
Age: mean 76, range 58–83
Female: 44%
Catheter: Unclear
General Practice No Delirium
ICD-10
Bacteriuria
Not Stated
UTI
Not Stated
2 out of 9 (22%) patients with delirium had UTI
Manepalli et al 1990 [64] Cross-Sectional; Retrospective 407 patients
Age: Not Stated
Female: Not Stated
Catheter: Unclear
Of the 14 patients with UTI and delirium
Age: 81.9 years, range 70–93
Hospital
(Psychogeriatric Unit)
Partial Delirium
ICD-9
Bacteriuria
Not Stated
UTI
ICD - 9
14 out of 83 (17%) patients with UTI had delirium
14 out of 54 (26%) patients with delirium had UTI
Rothberg et al. 2013 [65] Cohort; Retrospective 225,028
Age: ≥ 65 years,
median 82;
Female: 58%
Catheter: Unclear
Hospital
(Admissions)
No Delirium
Defined as on Day 3 or later prescribed an antipsychotic or placed into restraints
Bacteriuria
Not Stated
UTI
ICD-9-CM
944 out of 20,986 (4.5%) patients with UTI had delirium
Sabzwari et al. 2014 [73] Cross-Sectional; Retrospective 464 patients
Age: ≥ 65 years,
mean 72.7 SD 6.4;
Female: 42%
Catheter: Unclear
Hospital
(Admission)
Partial Delirium
Key words in clinical notes: acute confusion, acute mental status changes, fluctuating consciousness, acute agitation and organic brain syndrome
Bacteriuria
Not Stated
UTI
Not Stated
17 out of 43 (40%) patients with UTI had delirium
17 out of 101 (17%) patients with delirium had UTI
17% of patients with delirium had UTI compared to 7% of patients without delirium. Adjusted OR 3.1 (95% CI 1.5–6.8, p < 0.005)
Schultz et al 1991 [57] Cohort; Prospective 65 residents
Age: Not reported
Female: Unclear
Catheter: Unclear
Nursing Home Yes Delirium
Not Stated
Altered Mental Status
Not Stated
Bacteriuria
Not Stated
UTI
significant change in condition + new +ve urine culture (≥104 cfu/ml for gram positive or ≥ 5 × 104 cfu/ml for gram negative organisms)
+ ≥10 WBCs per high power field.
3.4% of residents with UTI had delirium
12% of residents with UTI had altered mental status
Silver et al. 2009 [58] Cohort; Prospective 335 Patients
Age: ≥ 18 years,
mean 68,
Female: 36%
Catheter: 51%
Hospital No Confusion or Altered Mental Status
Clinical Notes
Bacteriuria
> 104 cfu/ml on urine culture
Catheter: 102 cfu/mL on urine culture
UTI
Bacteriuria and either fever without another explanation or ≥ 1 urinary symptom
77 out of 137 (56%) patients with positive urine cultures had confusion or Altered mental status compared to 114 out of 198 (58%) patients with negative urine cultures (p = 0.82)
19 out of 34
(56%) UTI patients presented with confusion or altered mental status compared to 44 out of 67 (66%) patients with asymptomatic bacteriura (p = 0.17)
Sundvall 2014 [11] Cross-sectional; Prospective 421 residents
Age (Female): mean 87 years, SD 6.4, range 63–100
Age (Male): mean 85 years, SD 7.1, range 65–100
Female: 70%
Catheter: 0%
Nursing Home Partial Confusion
Nursing Clinical Notes
Bacteriuria
≥105 cfu/ml on urine culture or if signs of possible UTI present: ≥103 for E. coli or males with Klebsiella and E.Faecalis; or ≥ 104 women with Klebsiella and E.Faecalis.
UTI
Not Stated
3 out of 22 (14%) residents with confusion had bacteriuria
3 out of 135 (2.2%) residents with bacteriuria had confusion
Residents with bacteriuria were less likely to have confusion OR 0.15 (95% CI 0.033–0.68, p = 0.014)
Sundvall 2011 [69] Cross-sectional; Prospective 651 residents
Age (Female): mean 86 years, SD 7.4, range 46–102
Age (Male): mean 82 years, SD 7.8, range 54–99
Female: 74%
Catheter: 0%
Nursing Home Yes Confusion
Nursing Assessment
Bacteriuria
≥105 cfu/ml on urine culture or if signs of possible UTI present: ≥103 for E. coli or males with Klebsiella and E.Faecalis; or ≥ 104 women with Klebsiella and E.Faecalis.
UTI
Not Stated
Correlation between bacteriuria with E. Coli and confusion OR 1.8 (95% CI 0.96–3.6, p = 0.067)
Correlation between bacteriuria and confusion OR 1.9 (95% CI 1.0–3.5, p = 0.044)