Reference intervals are important estimates used to determine whether an individual is healthy or unhealthy. They are the most widely used decision making tool in medicine and heavily influence doctor’s decisions regarding patient care. Despite the abundance of reference interval research in the field of clinical chemistry, age-related reference intervals have yet to be well-established for elderly populations. Many physiological and biochemical changes have been documented to occur with age however limited attempts have been made to quantify these changes. As a result, it is typical in clinical practice to assess geriatric patient data using an adult reference interval. Such practices can result in over-medicalization, unnecessary medical procedures and/or missed diagnoses. This thesis aims to address this gap in literature by summarizing what geriatric reference intervals are available and by investigating how reference intervals are affected by the presence of morbidity, a common characteristic of the elderly.
The first chapter of the thesis introduces the reader to reference intervals, summarizes the current guidelines used in their determination and provides a rationale for the use of age-related reference intervals in geriatrics. Chapter 2 presents a systematic review that summarizes all available reference intervals for populations ≥65 years of age and the methodology used in their determination. Despite extreme variability in methodology, evidence suggests that geriatric reference intervals are significantly different from those of adults for many analytes. Chapter 3 presents a study that evaluates the effect morbidity has on reference intervals. In this study data from the National Health and Nutrition Examination Survey (NHANES) was used to calculate age-specific reference intervals for creatinine, a marker of kidney function known to increase with age. Findings suggest that the presence of morbidity significantly increases the upper limit for creatinine in elderly populations. Finally, the concluding chapter summarizes the overall findings of the thesis, proposes areas for future research and reinforces the importance of the above findings. / Thesis / Master of Science (MSc) / Reference intervals are estimates used to determine whether an individual is healthy or unhealthy. In particular this thesis investigates reference intervals for blood test results. Currently no age-specific reference intervals for the elderly are used clinically, instead the normalcy of a blood test result for an elderly person is based on adult reference intervals. This process may lead to over-medicalization or missed diagnoses in geriatrics. Within this thesis is a systematic review of the literature that was performed to capture any available reference intervals that have been published for populations greater than 65 years of age. It was determined that a multitude of geriatric reference intervals are available in literature but they are not used clinically and have no standardized methodology for their determination. Despite this lack of standardization, studies proved that geriatric reference intervals are significantly different from those of adult populations. Given that morbidity or the presence of disease is common in older patients it was suspected this may be a reason for the difference in reference intervals. A separate study was then performed to determine whether the presence of disease affects reference interval calculations. Results from this study showed that the presence of disease affects reference intervals in older individuals more so than younger individuals.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/15963 |
| Date | 11 1900 |
| Creators | Arseneau, Erika |
| Contributors | Balion, Cynthia, Health Research Methodology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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