No abstract

Because a group of people are at the same age, they should not be assessed the same way. To interpret results of laboratory tests in elderly is a complex task, where reference intervals are one part, but far from the only one, to take into consideration.

Rationale, aims and objectives Reference intervals provided by the laboratory are commonly established by measuring samples from apparently healthy subjects in the ages 18–65 years, excluding elderly individuals with chronic diseases and medication. The aim of our study was to establish whether current reference intervals for immune parameters and chemical biomarkers are valid for older individuals including those with chronic diseases, so‐called frail elderly. Methods Data from our cohort of 138 non‐infected nursing home residents (NHR), mean age 86.8 years, range 80–98, were compared with raw data, as basis for the development of reference intervals, obtained from reference populations, like blood donors (IgA, IgG, IgM, C3 and C4) and from the Nordic Reference Interval Project (NORIP) (alanine aminotransferase, albumin, aspartate aminotransferase, creatinine, gamma‐glutamyl transferase, lactate dehydrogenase, phosphate, sodium and urea). Immune parameters were measured by nephelometry and in NORIP the measurements were performed by means of different routine methods, in more than 100 laboratories. Results Only nine individuals (7%) of NHR were found to be free from chronic disease. C3, C4 (P < 0.001) and IgG levels (P < 0.05) were higher, while IgM levels (P < 0.001) were lower in NHR compared with reference blood donors. Levels of alanine aminotransferase, phosphate (P < 0.001), albumin (P < 0.05) and sodium (P < 0.01) were lower while creatinine and urea levels were higher (P < 0.001) in NHR compared with NORIP subjects. Conclusion Comparing laboratory results from elderly people with conventional reference intervals can be misleading or even dangerous, as normal conditions may appear pathological, or vice versa and thus lead to unnecessary or even harmful treatment.

There are only few studies with specific focus on predictors of survival in nursing home residents. The aim was to study whether 1-year changes in complete blood count (including haemoglobin, red blood cells, erythrocyte volume fraction, mean corpuscular volume, mean corpuscular haemoglobin concentration, white blood cells count, and platelet count), C-reactive protein and interleukin-1β (IL-1β), IL-1Ra, IL-6, IL-8 and IL-10, are associated with 8-year survival in elderly nursing home residents, aged >80 years. Methods: Complete blood count, C-reactive protein and interleukins were measured at baseline, after 6 and 12 months from 167 nursing home residents aged 80-101 years, mean age 88+4.5 years, 75% of whom were women. Dates of death were collected from the National Death Register 8 years after baseline. Results: Levels of haemoglobin, red blood cells and mean corpuscular haemoglobin concentration were lower after 1-year, but higher for mean corpuscular volume and IL-1β, compared to baseline or 6 month follow-up. In the Cox regression model with a time-dependent covariate, raised levels of Creactive protein and IL-8 were associated with reduced survival time. Conclusions: Elevated levels of C-reactive protein and IL-8 during 1-year follow-up were related to reduced lengths of survival in elderly nursing home residents.