Demographics, lifestyle, and cardiovascular and neuropathy characteristics of DPN compared with IPN
| Polyneuropathy entity | DPN | IPN | Univariate P value* | Multivariate P value† |
| Demographics | ||||
| Participants | N1=214 | N2=88 | ||
| Male, n (%)‡ | 136 (63.6) | 50 (56.8) | 0.27 | |
| Age (years), median (IQR)§ | 67.4 (59.0–72.3) | 59 (49–70) | <0.001 | |
| Duration of neuropathy symptoms (years), n (%)¶ | 0.02 | 0.01 | ||
| 0–5 | 112 (65.1) | 70 (79.5) | ||
| >5 | 60 (34.9) | 18 (20.5) | ||
| Lifestyle and cardiovascular characteristics | ||||
| BMI (kg/m2) | 32.0 (27.7–36.0) | 27.5 (24.4–29.8) (1) | <0.0001 | <0.001 |
| Waist circumference (cm) | 110 (99–120) (1) | 97 (87–108) (1) | <0.0001 | <0.001 |
| SBP (mm Hg) | 138 (129–151) | 134 (122–145) (1) | 0.02 | 0.15 |
| DBP (mm Hg) | 83 (77–90) | 81 (74–91) (1) | 0.32 | 0.17 |
| Hypertension, n (%) | 156 (72.9) | 27 (30.7) | <0.001 | <0.001 |
| HbA1c (mmol/mol) | 50 (45–57) (3) | 36 (34–37) (1) | <0.0001 | <0.001 |
| Cholesterol (mmol/L) | 4.0 (3.4–4.6) (3) | 5.2 (4.4–6.0) (1) | <0.0001 | <0.001 |
| LDL (mmol/L) | 1.9 (1.5–2.4) (10) | 3.1 (2.3–3.6) (1) | <0.0001 | <0.001 |
| HDL (mmol/L) | 1.2 (1.0–1.4) (3) | 1.4 (1.1–1.7) (1) | <0.0001 | <0.001 |
| Statin users, n (%) (missing) | 171 (81.8) (5) | 17 (19.3) | <0.001 | <0.001 |
| Alcohol overuse, n (%) | 23 (10.8) | 5 (5.8) | 0.18 | 0.28 |
| Current smokers, n (%) (missing) | 33 (15.6) (2) | 19 (21.6) | 0.20 | 0.57 |
| Peripheral artery disease, n (%) | 10 (4.7) | 4 (4.6) | 1.0. | 0.6 |
| Macrovascular disease, n (%) | 51 (25.0) (10) | 12 (13.6) | 0.03 | 0.26 |
| Neuropathy measures | ||||
| UENS total score | 9.0 (5.0–16.0) | 8.0 (3.0–14.0) (1) | 0.02 | 0.41 |
| NSS | ||||
| Bulbar paresis | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) (1) | 0.02 | |
| Extremity paresis | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) (1) | 0.2 | |
| Sensory positive | 2.0 (1.0–2.0) | 2.0 (1.0–2.0) (1) | 0.74 | |
| Sensory negative | 0.0 (0.0–1.0) | 0.0 (0.0–1.0)(1) | <0.001 | |
| Autonomic | 1.0 (0.0–1.0) | 0 (0.0–0.0) (1) | <0.0001 | |
| Total | 3.0 (2.0–4.3) | 2.1 (2.0–3.2) (1) | 0.01 | 0.002 |
| NPSI** | ||||
| Total score | 28 (13.5–42.5) (1) | 28(15-39)(1) | 0.65 | 0.27 |
| Evoked pain score | 6 (0–12) (1) | 3 (0–8) (1) | 0.09 | 0.04 |
| QST, n (%) (missing) | ||||
| Increased VDT | 107 (55.4) (21) | 61 (69.3) | 0.03 | <0.01 |
| Increased MDT | 71 (33.6) (3) | 35 (39.8) | 0.31 | 0.1 |
| Increased CDT and/or WDT | 62 (29.4) (3) | 33 (37.5) | 0.17 | 0.08 |
| DMA | 14 (6.6) | 18 (20.5) | <0.001 | <0.01 |
| Increased MPS | 11 (5.2) (3) | 16 (18.2) | <0.001 | <0.01 |
| IENFD (fibres/mm) | 3.2 (1.5–5.5) (28) | 4.9 (3.6–6.2) | <0.0001 | <0.001 |
| Abnormal IENFD, n (%) (missing) | 95 (51.1) (28) | 26 (29.6) | <0.01 | <0.001 |
| Abnormal NCS, n (%) (missing) | 78 (37.1) (4) | 35 (39.8) | 0.67 | 0.25 |
*P value of <0.05 chosen as level of significance. Rank-sum test, χ2 test and Fisher’s exact test were used as appropriate.
†P value of <0.05 chosen as level of significance. Linear regression is used for interval variables and logistic regression for categorical variables with adjustment for age and sex for all variables.
‡All categorical variables are stated as frequency with percentage in parentheses and missing in parentheses if present, n (%) (missing).
§All interval variables are stated as median with IQR between brackets and missing between parentheses if present, median (IQR) (missing).
¶A total of 174 out of 214 patients with DPN have symptoms of polyneuropathy, whereas all patients with IPN are symptomatic. Duration of symptoms is missing for two patients with DPN. The frequencies are stated as proportions out of all patients with non-missing on duration of neuropathy symptoms.
**NPSI total score and evoked pain score for 97 patients with DPN and 52 patients with IPN with distal pain in both feet.
BMI, body mass index; CDT, cold detection threshold; DBP, diastolic blood pressure; DMA, dynamic mechanical allodynia; DPN, diabetic polyneuropathy; HbA1c, glycosylated haemoglobin; HDL, high-density lipoprotein; IENFD, intraepidermal nerve fibre density; IPN, idiopathic polyneuropathy; LDL, low-density lipoprotein; MPS, mechanical pain sensitivity; NCS, nerve conduction studies; NPSI, Neuropathic Pain Symptom Inventory; NSS, Neuropathy Symptom Score; QST, quantitative sensory testing; SBP, systolic blood pressure; UENS, Utah Early Neuropathy Score; VDT, vibration detection threshold; WDT, warmth detection threshold.