fetching data ... 
Background: Nailfold videocapillaroscopy (NVC) is essential for assessing microcirculation in Raynaud’s phenomenon and systemic sclerosis. However, normative findings in healthy populations at high altitude, particularly using artificial intelligence (AI), remain limited.
Objectives: To characterize NVC findings in Colombian adults without systemic autoimmune rheumatic disease or Raynaud’s phenomenon living above 2,500 meters, using AI-based quantitative analysis, and to explore associations with lifestyle factors and birth altitude.
Methods: A cross-sectional study was conducted in Bogotá, Colombia. Adults without autoimmune disease or Raynaud’s phenomenon underwent standardized NVC (32 images/participant). Images were analyzed with Capillary.io, an automated AI software. Morphological and quantitative variables were assessed using ANOVA or Kruskal–Wallis, chi-square tests, and correlations with Holm adjustment.
Results: Mean age was 37.7 ± 16.3 years (50% women). Capillary density increased with age (p < 0.001). Tortuosity was higher in adults older than 60 years (p = 0.012). No megacapillaries, avascular areas, or scleroderma patterns were observed. Arterial diameters decreased progressively with age (p < 0.001). BMI, exercise, and sleep showed no correlations with NVC parameters, while smoking was associated with larger apical diameters (p = 0.018). Participants born above 2,000 meters exhibited a higher proportion of normal capillaries (p = 0.049) and fewer abnormalities (p = 0.003).
Conclusions: Healthy individuals living at high altitude show preserved capillary density, few abnormalities, and age-related changes mainly involving tortuosity and arterial caliber. Birth altitude was associated with fewer abnormalities, suggesting microvascular adaptation to hypobaric hypoxia. These findings offer contextualized normative reference values.
Baseline characteristics
| Age group | |||||
|---|---|---|---|---|---|
| Characteristic | Overall | 18-30 Y | 31-60 Y | >60 Y | p-value |
| N = 144 1 | N = 72 1 | N = 48 1 | N = 24 1 | ||
| Female sex | 72 (50%) | 36 (50%) | 24 (50%) | 12 (50%) | >0.9 2 |
| Residence time, years | 23.0 (0.2, 78.0) | 16.0 (0.2, 30.0) | 24.0 (0.2, 58.0) | 61.0 (0.5, 78.0) | <0.001 3 |
| Lifestyle habits | |||||
| Exercise, h/week | 3.0 (0.0, 25.0) | 3.0 (0.0, 25.0) | 3.0 (0.0, 10.0) | 1.5 (0.0, 9.0) | 0.2 3 |
| Sleep, h/day | 6.0 (3.0, 8.0) | 6.0 (5.0, 8.0) | 6.0 (3.0, 8.0) | 7.0 (5.0, 8.0) | 0.2 3 |
| BMI, kg/m 2 | 24.4 (16.1, 34.7) | 22.9 (18.4, 34.2) | 25.6 (18.4, 34.7) | 26.9 (16.1, 34.2) | < 0.001 3 |
| Underweight | 3 (2.1%) | 1 (1.4%) | 1 (2.1%) | 1 (4.2 %) | 0.7 4 |
| Normal | 80 (56%) | 53 (74%) | 20 (42%) | 7 (29 %) | < 0.001 2 |
| Overweight | 47 (33%) | 14 (19%) | 20 (42%) | 13 (54 %) | 0.002 2 |
| Comorbidities | |||||
| Obesity | 14 (9.7 %) | 4 (5.6 %) | 7 (15 %) | 3 (13 %) | 0.2 4 |
| Hypothyroidism | 10 (6.9 %) | 2 (2.8 %) | 4 (8.3 %) | 4 (17 %) | 0.058 4 |
| HTN | 11 (7.6 %) | 0 (0 %) | 5 (10 %) | 6 (25 %) | < 0.001 4 |
| Depression | 6 (4.2 %) | 5 (6.9 %) | 1 (2.1 %) | 0 (0 %) | 0.3 4 |
| T2DM | 3 (2.1 %) | 0 (0 %) | 1 (2.1 %) | 2 (8.3 %) | 0.031 4 |
| Anxiety | 4 (2.8 %) | 4 (5.6 %) | 0 (0 %) | 0 (0 %) | 0.2 4 |
| Dyslipidemia | 3 (2.1 %) | 0 (0 %) | 1 (2.1 %) | 2 (8.3 %) | 0.031 4 |
| Cigarette/vaper Use | 15 (10 %) | 7 (9.7 %) | 5 (10 %) | 3 (13 %) | > 0.9 4 |
| Packs/year | 6.0 (2.5, 12.5) | 2.8 (2.5, 3.0) | 5.0 (2.5, 7.5) | 10.0 (6.0, 12.5) | 0.2 3 |
| Medications | |||||
| Hypolipidemic agents | 4 (2.8 %) | 0 (0 %) | 1 (2.1 %) | 3 (13 %) | 0.006 4 |
| Antidepressants | 9 (6.3 %) | 6 (8.3 %) | 2 (4.2 %) | 1 (4.2 %) | 0.7 4 |
| Anticoagulants | 2 (1.4 %) | 0 (0 %) | 0 (0 %) | 2 (8.3 %) | 0.027 4 |
| ACEI | 2 (1.4 %) | 0 (0 %) | 1 (2.1 %) | 1 (4.2 %) | 0.2 4 |
| ARB | 9 (6.3 %) | 0 (0 %) | 4 (8.3 %) | 5 (21 %) | < 0.001 4 |
| BB | 4 (2.8 %) | 1 (1.4 %) | 0 (0 %) | 3 (13 %) | 0.015 4 |
HTN: Hypertension; T2DM: Type 2 Diabetes Mellitus; ACEI: Angiotensin-Converting Enzyme Inhibitor; ARB: Angiotensin Receptor Blocker; BB: Beta-Blocker
1 n (%); Median (Min, Max)
2 Pearson’s Chi-squared test
3 Kruskal-Wallis rank sum test
4 Fisher’s exact test
Videocapillaroscopy characteristics and morphological capillary segment alterations by age group
| Age group | |||||
|---|---|---|---|---|---|
| Characteristic | Overall | 18-30 Y | 31-60 Y | > 60 Y | p-value |
| N = 144 1 | N = 72 1 | N = 48 1 | N = 24 1 | ||
| Total analyzed, mm | 45.6 ± 9.3 | 47.5 ± 8.8 | 43.8 ± 8.5 | 43.7 ± 11.4 | 0.048 2 |
| Capillary density per mm | 8.4 ± 0.7 | 8.2 ± 0.6 | 8.4 ± 0.7 | 8.9 ± 0.9 | <0.001 2 |
| Total capillaries, n | 383.6 ± 88.8 | 391.7 ± 82.1 | 368.8 ± 83.1 | 389.2 ± 115.7 | 0.4 2 |
| Normal capillaries, n | 260.0 ± 69.6 | 261.0 ± 69.8 | 260.4 ± 65.5 | 256.2 ± 79.3 | >0.9 2 |
| Normal capillaries, % | 68.7 ± 12.6 | 67.6 ± 14.1 | 71.1 ± 10.8 | 67.3 ± 10.8 | 0.3 2 |
| Total abnormal capillaries, n | 0.6 ± 1.3 | 0.6 ± 1.2 | 0.8 ± 1.6 | 0.0 ± 0.2 | 0.052 2 |
| Total abnormal capillaries, % | 0.1 ± 0.3 | 0.1 ± 0.3 | 0.2 ± 0.4 | 0.0 ± 0.1 | 0.050 2 |
| Dilated capillaries, n | 92.6 ± 61.2 | 102.3 ± 68.1 | 79.3 ± 47.9 | 90.4 ± 59.8 | 0.13 2 |
| Dilated capillaries, % | 23.3 ± 13.0 | 25.2 ± 14.7 | 21.0 ± 10.9 | 22.1 ± 10.7 | 0.2 2 |
| Tortuous capillaries, n | 41.1 ± 27.3 | 38.7 ± 25.8 | 36.9 ± 23.8 | 56.8 ± 33.3 | 0.007 2 |
| Tortuous capillaries, % | 10.5 ± 6.3 | 9.7 ± 5.6 | 9.9 ± 6.2 | 14.0 ± 7.5 | 0.012 2 |
| Capillary flow | 0.7 3 | ||||
| Normal | 103 (72 %) | 51 (71 %) | 32 (67 %) | 20 (83 %) | |
| Granular | 11 (7.6 %) | 6 (8.3 %) | 4 (8.3 %) | 1 (4.2 %) | |
| Slow | 30 (21 %) | 15 (21 %) | 12 (25 %) | 3 (13 %) | |
| Edema | 1 (0.7 %) | 0 (0 %) | 1 (2.1 %) | 0 (0 %) | 0.5 3 |
| Hemorrhages, n | 0.7 ± 1.6 | 0.9 ± 1.9 | 0.5 ± 1.1 | 0.5 ± 1.1 | 0.4 2 |
| Venous plexus | 107 (74 %) | 54 (75 %) | 32 (67 %) | 21 (88 %) | 0.2 4 |
| Apical | |||||
| Total, µm | 17.2 ± 1.8 | 17.5 ± 1.9 | 17.0 ± 1.5 | 16.9 ± 1.7 | 0.3 2 |
| Normal capillaries, µm | 15.2 ± 0.9 | 15.4 ± 0.9 | 15.1 ± 0.8 | 14.8 ± 0.9 | 0.012 2 |
| Dilated capillaries, µm | 23.3 ± 0.9 | 23.1 ± 0.8 | 23.5 ± 0.9 | 23.5 ± 1.0 | 0.048 2 |
| Tortuous capillaries, µm | 17.6 ± 2.3 | 17.7 ± 2.3 | 17.7 ± 2.4 | 17.5 ± 2.1 | >0.9 2 |
| Arterial | |||||
| Total, µm | 10.8 ± 1.3 | 11.2 ± 1.4 | 10.5 ± 0.9 | 10.1 ± 1.1 | <0.001 2 |
| Normal capillaries, µm | 9.9 ± 0.9 | 10.2 ± 1.0 | 9.7 ± 0.8 | 9.3 ± 0.8 | <0.001 2 |
| Dilated capillaries, µm | 12.8 ± 1.4 | 13.3 ± 1.3 | 12.7 ± 1.0 | 11.9 ± 1.7 | <0.001 2 |
| Tortuous capillaries, µm | 12.2 ± 1.5 | 12.5 ± 1.6 | 11.9 ± 1.3 | 11.6 ± 1.1 | 0.011 2 |
| Venous | |||||
| Total, µm | 14.3 ± 1.3 | 14.5 ± 1.5 | 14.1 ± 1.0 | 13.9 ± 1.1 | 0.065 2 |
| Normal capillaries, µm | 13.2 ± 0.8 | 13.3 ± 0.9 | 13.1 ± 0.6 | 12.9 ± 0.7 | 0.062 2 |
| Dilated capillaries, µm | 17.1 ± 1.4 | 17.3 ± 1.4 | 17.1 ± 1.2 | 16.7 ± 1.6 | 0.2 2 |
| Tortuous capillaries, µm | 15.3 ± 1.8 | 15.5 ± 1.9 | 15.0 ± 1.7 | 14.9 ± 1.3 | 0.2 2 |
1 Mean ± SD; n (%)
2 One-way analysis of means
3 Fisher’s exact test
4 Pearson’s Chi-squared test
REFERENCES: NIL.
Acknowledgments: NIL.
Disclosure of Interests: None declared.