Study limitations
In addition to the inherent limitations of a retrospective study this study had further study limitations:
  1. A minority of subjects were older than age 60 years, due to a lower life expectancy in a South African population (the average life expectancy of an adult in 2014 was estimated at 59.1 years for males and 63.1 years for females, according to Statistics South Africa),(41)
  2. RA strain measurement values vary with different vendors and software packages,
  3. exercise capacity of the study subjects was not assessed to unmask subclinical diastolic dysfunction and symptoms, and
  4. Being a secondary data analysis, sample size was restricted to what was collected in the parent study, a larger sample size might have been able to detect finer differences.
  5. Majority of the patients were obese or overweight and is a reflection of the current “normal” South African population.
  6. We did not do blood tests to screen for diseases such as diabetes, renal dysfunction and hyperlipidaemia or additional imaging or biomarkers for assessment of fibrosis.
Conclusion
We have presented the first normative values for RALS in sub-Saharan African population. Normal ageing was associated with a trend towards declining RALS with preserved RAVI, and BMI was inversely related to RALS. The normative data on RA strain and volumes according to age, will help in differentiating normal from abnormal RA function and thus help in cardiovascular diseases risk stratification in this population. Further, this study provides a platform for future larger studies on RALS.
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