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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)