Table 2.
Characteristics (%) of ≥ 50 years old patients initiating metformin (MET) and sulfonylurea (SU) from the Veterans Health Administration (VHA; FY2002 to FY2012) and Kaiser Permanente Washington State (KPWA; 1996–2012) health care systems before balancing characteristics using inverse probability of treatment weighting
| VHA (n=75,187) |
KPWA (n=10,866)a |
|||||||
|---|---|---|---|---|---|---|---|---|
| Covariates | MET (n=56,972) | SU (n=18,215) | p-value | SMD %b | MET (n=7,546) | SU (n=3,320) | p-value | SMD % |
| Index year | <.0001 | <.0001 | ||||||
| 1996–1998 | - | - | - | 5.9 | 28.6 | −62.8% | ||
| 1999–2000 | - | - | - | 6.2 | 19.2 | −39.6% | ||
| 2001–2002 | - | - | - | 9.7 | 14.5 | −14.6% | ||
| 2002–2004 | 4.6 | 8.8 | −16.9% | - | - | - | ||
| 2003–2004 | - | - | - | 12.3 | 11.8 | 1.4% | ||
| 2005–2006 | 28.8 | 44.0 | −31.9% | 16.2 | 11.1 | 14.9% | ||
| 2007–2008 | 26.9 | 24.1 | 6.4% | 17.2 | 6.6 | 33.4% | ||
| 2009–2012 | - | - | - | 32.5 | 8.3 | 62.7% | ||
| 2009–2010 | 22.8 | 14.7 | 20.9% | - | - | - | ||
| 2011–2012 | 16.9 | 8.4 | 25.8% | - | - | - | ||
| Sociodemographic-related | ||||||||
| Age, mean (±sd) | 60.0 (±8.0) | 63.5 (±9.4) | <.0001 | −40. 3% | 61.0 (±7.8) | 67.8 (±10.9) | <.0001 | −72.3% |
| Age category | ||||||||
| 50–64 | 70.8 | 54.2 | 34.9% | 71.0 | 40.8 | 63.9% | ||
| 65–74 | 23.0 | 29.7 | <.0001 | −15.4% | 22.3 | 27.8 | <.0001 | −12.8% |
| ≥ 75 | 6.2 | 16.1 | −31.8% | 6.8 | 31.5 | −66.2% | ||
| Male gender | 96.6 | 97.5 | <.0001 | −5.2% | 49.6 | 52.4 | .007 | −5.6% |
| Race | ||||||||
| White | 83.9 | 84.4 | −1.4% | 73.4 | 76.8 | −7.8% | ||
| Black | 14.1 | 13.8 | .076 | 0.8% | 4.3 | 3.8 | 2.3% | |
| Asian | - | - | 7.8 | 6.8 | .001 | 3.8% | ||
| Other | 2.0 | 1.7 | 1.8% | 3.3 | 2.2 | 6.7% | ||
| Unknown | - | - | 11.2 | 10.4 | 2.7% | |||
| Married | 59.1 | 59.6 | .222 | −1.0% | - | - | ||
| Low nSES c | 49.4 | 51.7 | <.0001 | −4.6% | 50.2 | 48.8 | .174 | 2.8% |
| VHA only insurance | 47.2 | 41.6 | <.0001 | 11.4% | - | - | ||
| Medicaid/Medicare | 30.4 | 58.2 | <.0001 | −58.3% | ||||
| High healthcare utilization d | 24.7 | 25.9 | .001 | −2.7% | 21.7 | 31.9 | <.0001 | −23.2% |
| Diabetes-related | ||||||||
| Diabetic nephropathy | 1.1 | 1.6 | <.0001 | −4.7% | 2.0 | 1.6 | .095 | 3.6% |
| Diabetic retinopathy | 4.8 | 6.6 | <.0001 | −7.9% | 2.6 | 4.4 | <.0001 | −9.8% |
| Diabetic neuropathy | 6.7 | 8.6 | <.0001 | −7.1% | 8.1 | 8.6 | .438 | −1.6% |
| HbA1c value, mean (±sd) | 7.2 (±1.4) | 7.4 (±1.6) | <.000 1 | −15.8% | 8.4 (±1.9) | 8.9 (±2.2) | <.0001 | −23.5% |
| HbA1c category | ||||||||
| < 7 | 53.0 | 45.4 | 15.2% | 19.3 | 14.2 | 13.7% | ||
| 7–8 | 30.7 | 32.1 | <.0001 | −3.0% | 30.7 | 25.7 | <.0001 | 11.1% |
| > 8 | 16.3 | 22.5 | −15.6% | 50.0 | 60.1 | −20.4% | ||
| Creatinine value, mean (±sd) | 1.0 (±0.2) | 1.1 (±0.2) | <.0001 | −27.3% | 0.9 (±0.2) | 1.0 (±0.2) | <.0001 | −42.6% |
| Other comorbidities | ||||||||
| Obesity | 62.2 | 51.1 | <.0001 | 22.5% | 57.9 | 33.1 | <.0001 | 51.5% |
| Hypertension | 90.6 | 91.6 | <.0001 | −3.6% | 59.5 | 54.1 | <.0001 | 11.0% |
| Hyperlipidemia | 87.6 | 84.8 | <.0001 | 8.4% | 44.6 | 29.9 | <.0001 | 25.1% |
| Stroke | 6.3 | 8.3 | <.0001 | −7.7% | 1.7 | 3.4 | <.0001 | −28.4% |
| Ischemic heart disease | 46.1 | 53.0 | <.0001 | −13.9% | 12.9 | 22.4 | <.0001 | −25.0% |
| Congestive heart failure | 15.7 | 23.4 | <.0001 | −19.7% | 3.3 | 10.3 | <.0001 | −28.4% |
| Atrial fibrillation | 11.9 | 17.4 | <.0001 | −15.6% | 4.7 | 11.4 | <.0001 | −25.0% |
| Traumatic brain injury | 6.3 | 6.1 | .376 | 0.8% | 1.3 | 1.6 | .129 | −3.1% |
| Vitamin B12 deficiency | 4.7 | 5.3 | .001 | −2.7% | 0.7 | 1.0 | .134 | −3.0% |
| Psychiatric and substance comorbidities | ||||||||
| Depression | 29.6 | 25.4 | <.0001 | 9.5% | 4.4 | 4.6 | .706 | −0.8% |
| PTSD | 20.6 | 16.2 | <.0001 | 11.3% | 0.5 | 0.2 | .012 | 5.7% |
| Other anxiety e | 14.0 | 12.7 | <.0001 | 3.8% | 3.1 | 2.1 | .008 | 5.7% |
| Bipolar disorder | 8.1 | 6.6 | <.0001 | 5.9% | 1.9 | 1.1 | .002 | 6.9% |
| Schizophrenia | 5.6 | 5.2 | .028 | 1.9% | 0.3 | 0.3 | .855 | −0.4% |
| Nicotine dependence/smoker | 53.6 | 51.6 | <.0001 | 4.0% | 17.5 | 16.5 | .184 | 2.8% |
| Alcohol abuse/dependence | 16.5 | 14.7 | <.0001 | 4.9% | 1.7 | 2.2 | .082 | −3.5% |
| Illicit drug abuse/dependence | 8.3 | 7.5 | .0004 | 3.0% | 0.6 | 0.6 | .755 | 0.7% |
| Other medications f | ||||||||
| Statins | 70.3 | 67.0 | <.0001 | 7.1% | 39.5 | 31.2 | <.0001 | 17.4% |
| Anticholinergics | 45.6 | 43.5 | <.0001 | 4.2% | 22.2 | 26.2 | <.0001 | −9.3% |
| NSAIDs | 57.6 | 51.3 | <.0001 | 12.7% | 18.7 | 20.0 | .112 | −3.3% |
| Antihypertensives | 87.4 | 88.6 | <.0001 | −3.6% | 44.4 | 44.6 | .866 | −0.4% |
KPW dynamic cohort – covariates measured for 2 year prior to every new metformin/sulfonylurea start; VHA=Veterans Health Administration; KPW=Kaiser Permanente Washington State; FY=Fiscal Year; MET=Metformin; SU=Sulfonylurea;
SMD % = Standardized mean difference percent comparing MET to SU, SMD% >10 considered a large difference; nSES = neighborhood socioeconomic status,
nSES = top 50th vs. bottom 50th percentile of neighborhood socioeconomic status based on information from 7 measures of SES obtained from 2009–2013 5-year census estimates from the American Community Survey
High healthcare utilization-top 25th percentile of mean visits per month
Other anxiety disorders = panic disorder, OCD, social phobia, GAD, Anxiety NOS
Other medications associated with dementia= sustained use prior to MET or SU (at least 2 fills in a 6 month period)