First, a unique biomedical testbed based on non-invasive devices was designed. In order to develop appropriately tailored health tests for participants from Lindängen, specific devices were used, which were less intrusive compared to conventional devices. For instance, blood pressure was measured on the wrist instead of the upper arm, Fig. 1(a). Measurements of body composition were performed using bioelectrical impedance analysis instead of using tape measurements, thus limiting direct body contact to a minimum, Fig. 1(b). Additional non-invasive devices were also included in the health test, viz. the cardiovascular diagnostic complex AngioScan-01, Fig. 1(c), and the non-invasive blood analyzer, BG20, Fig. 1(d), to achieve a comprehensive non-invasive biomedical test.
Second, for biomedical test 56 volunteers from Lindängen for were identified. 17 of these participants did not fully complete the biomedical tests and were therefore excluded from data analysis. Thus, a total of 39 female volunteers, aged 25-77 years, participated in this study. Participants were of Middle Eastern origin (Supplementary Information, Supplementary Table S1).
Biomedical tests revealed that 25.6% (n=10) of the participants had blood pressures outside of the reference interval, Fig. 2(a)-3(b), whereas only 2.6% (n=1) had a RHR outside of the reference interval, Fig. 2(c). The reference intervals for SBP and DBP, as well as RHRs, were defined according to Refs. [21; 22].
In accordance with the literature, overweight and obesity are defined by BMIs of ≥25 kg/m2 and ≥30 kg/m2, respectively [23]. Thus, 25.6% (n=10) of the participants were considered to be overweight and 51.3% (n=20) were obese, Fig 3.
More than half of the participants had body fat percentages above the reference intervals, Figs. 4(a)-4(c), i.e. 21-33% of body fat for 20-39 year olds, 24-34% of body fat for 40-59 year olds, and 25-36% of body fat for 60-79 year old individuals [24].
VA and SI were also determined based on RHR, stiffness of blood vessels, and differences of arterial pressure [25] using the professional dual-channel cardiovascular complex, Fig. 5. According to the manufacturer, the reference interval for the stress index is 0-150 units, whereas VA should be equal to or below the age of the participant [25]. It was found that many volunteers had both parameters above the cut-off values, Fig. 5.
Moreover, Hb and Glu concentrations in blood were determined non-invasively, Fig. 6. Interestingly, almost all obtained values were within the reference intervals, 120-160 g/L for Hb and 2.8-11.1 mM/L for Glu [26].
In parallel, the Quality of Life-BREF survey was distributed among the participants. Table 1 shows the obtained QoL scores. All the mean domain scores were around the fifty-percentage mark, meaning that the sample were distributed in relative equal proportions around the cut-off level for satisfaction in quality of life. However, about half of the participants (n=17) had domain scores lower than the satisfactory level.
Table 1 QOL scores of participants
WHOQOL-BREF score (scale)
|
Mean score (SD)
|
Score range
|
Physical health domain
|
54.3 (19.3)
|
0 – 100
|
Psychological domain
|
54.0 (15.9)
|
0 – 100
|
Social relationships domain
|
63.8 (18.8)
|
0 – 100
|
Environmental domain
|
56.0 (16.7)
|
0 – 100
|
Health related quality of life global item
|
3.5 (0.9)
|
0 – 5
|
Health satisfaction global item
|
3.9 (1.1)
|
0 – 5
|
Third, detailed statistical analysis of the data was performed. In absence of a relevant model, nonparametric correlation statistics was initially exploited. This analysis (Spearman’s and Kendal’s rank tests) revealed no significant correlation between the four QoL domain scores/two of the global items and biomedical metrics. This was unsurprising since the dependence between perceived health and biomedical metrics is a priori complex. In other words, it is hard to envision strong linear dependences between participant-perceived QoL scores and individual biomedical parameters, such as body composition parameters, RHR, blood pressure, etc, using a univariate regression analysis. Thus, multivariate regression analysis of all the data collected was carried out. The identification of variables, which statistically significantly correlate (p-value < 0.05) was performed using a meta-modelling approach. As expected, linear multi-variable models failed to provide any statistically significant correlations. Indeed, a 2-term set of all possible models with inclusion of linear, inverted, squared, and pairwise multiplied variables was investigated to identify statistically important variables. A set of identified statistically significant variables, which are presented in Supplementary Table S2, was used to build all possible 4-term models, which were tested, and the best model was selected for each case.
The social relationships domain and health related QoL global item scores have no statistically significant correlations with variables. The best model found to describe physical health domain scores is presented in Equation 1, while the statistical properties of the model are provided in ANOVA Supplementary Table S3.
-22.2452 + 1799.6/BMI + 0.0157277.FM.VA - 0.000567556.VA.SI (1)
As one can see from Supplementary Table S3, all coefficients are statistically significant. On the one hand, the model shows that larger BMI lowers expected physical health domain scores. On the other hand, surprisingly, larger FM and VA, rise physical health domain scores. However, it should be noted that there is a linear correlation between variables FM and BMI, and hence it may be a manifestation of the approximate quadratic dependence on BMI. The SI in synergy with VA lower physical health domain scores. The physical health domain scores predicted by the model have a 0.533 statistically significant correlation coefficient with a p-value of 0.00048.
The best model found to describe psychological domain scores is presented in Equation 2, while the statistical properties of the model are provided in ANOVA Supplementary Table S4.
-20.2236 - 1092.97/Age + 2257.35/BMI + 0.0218865.FM.BMI (2)
As one can see from Supplementary Table S4, all coefficients are statistically significant. Age tends to lower psychological domain scores, however, with increasing age, the negative impact on psychological domain scores is attenuated. Psychological domain scores are increased by smaller BMIs and by a synergistic interaction of BMI with FM. The psychological domain scores predicted by the model have a 0.606 statistically significant correlation coefficient with a p-value of 0.000043.
The best model found to describe environmental domain scores is presented in Equation 3, while the statistical properties of the model are provided in ANOVA Supplementary Table S5.
70.5533 - (8.39801.RHR)/Age (3)
As one can see from Supplementary Table S5, the coefficient is statistically significant. Age tends to inversely lower environmental domain scores and the effect is attenuated with age and increases with RHR. The environmental domain scores predicted by the model have a weakly statistically significant correlation coefficient of 0.32 with a p-value of 0.046.
The best model found to describe health satisfaction is presented in Equation 4, while the statistical properties of the model are provided in ANOVA Supplementary Table S6.
-2.73262+84.1044/FM+0.000445315 Age.FM+0.000449529 SBP.FM (4)
As one can see from Supplementary Table S6, all calculated coefficients are statistically significant. FM has an inverse positive effect on health satisfaction scores, which are synergistically weakly affected by Age and SBP. The health satisfaction scores predicted by the model have a 0.612 statistically significant correlation coefficient with a p-value of 0.000035.