A framework for employing longitudinally collected multicenter electronic health records to stratify heterogeneous patient populations on disease history

OBJECTIVE

To facilitate patient disease subset and risk factor identification by constructing a pipeline which is generalizable, provides easily interpretable results, and allows replication by overcoming electronic health records (EHRs) batch effects.

MATERIAL AND METHODS

We used 1872 billing codes in EHRs of 102 880 patients from 12 healthcare systems. Using tools borrowed from single-cell omics, we mitigated center-specific batch effects and performed clustering to identify patients with highly similar medical history patterns across the various centers. Our visualization method (PheSpec) depicts the phenotypic profile of clusters, applies a novel filtering of noninformative codes (Ranked Scope Pervasion), and indicates the most distinguishing features.

RESULTS

We observed 114 clinically meaningful profiles, for example, linking prostate hyperplasia with cancer and diabetes with cardiovascular problems and grouping pediatric developmental disorders. Our framework identified disease subsets, exemplified by 6 "other headache" clusters, where phenotypic profiles suggested different underlying mechanisms: migraine, convulsion, injury, eye problems, joint pain, and pituitary gland disorders. Phenotypic patterns replicated well, with high correlations of ≥0.75 to an average of 6 (2-8) of the 12 different cohorts, demonstrating the consistency with which our method discovers disease history profiles.

DISCUSSION

Costly clinical research ventures should be based on solid hypotheses. We repurpose methods from single-cell omics to build these hypotheses from observational EHR data, distilling useful information from complex data.

CONCLUSION

We establish a generalizable pipeline for the identification and replication of clinically meaningful (sub)phenotypes from widely available high-dimensional billing codes. This approach overcomes datatype problems and produces comprehensive visualizations of validation-ready phenotypes.

[Tetragastrin activation of rat gastric mucosa adenyl cyclase in vitro]

The effect of tetragastrin and histamine on the adenylate cyclase activity of the rat gastric mucosa was examined in vitro. Tetragastrin and histamine were demonstrated to stimulate the activity of the enzyme in question. The antagonist of histamine H2-receptors, cimetidine inhibits the stimulatory effect of histamine in vitro and activates tetragastrin stimulation of the adenylate cyclase activity. It is suggested that tetragastrin and histamine activate adenylate cyclase of the rat gastric mucosa via different receptors.

[Importance of cooling after death for restoration of metabolism during resuscitation]

Incorporation of labelled metabolites into proteins, RNA and DNA was completely inhibited in rabbit tissues under conditions of prolonged hypothermia (10 degrees). The incorporation of labelled metabolites into all the biopolymers studied was restored after subsequent warming up to 38 degrees. Within 60-90 min after death of the animals due to acute anoxia, the labelled metabolites did not incorporate into protein, RNA and DNA. Artificial postmortal hypothermia (20 degrees) increased (by about 2.5-3-fold) the period of viability, during which reanimation is possible. The hypothermia enables subsequent restoration of the anabolic processes from the zero level.

Protein degradation to low-molecular compounds after death and during reanimation

The process of protein degradation to amino acids and peptides in rabbits following death and during reanimation in terms of the effects of artificial postmortem cooling on that process has been studied. Protein degradation was judged by increase of low-molecular nitrogenous compounds in serum and in organs by increase in soluble radioactivity with time in animals the proteins of which had been marked in vivo with radioisotopes. It has been found that immediately after death resulting from acute anoxia the processes of protein degradation to amino acids as well as synthesis stops in liver, skeletal and cardiac muscles, spleen, brain and spinal cord. Similar phenomenon takes place in the case of deep hypothermy. During reanimation the process of protein degradation to low-molecular compounds in organs restores.

Restoration of nucleic acid biosynthesis after clinical death and factors stimulating the process in vivo

The biosynthesis of RNA and DNA falls almost to zero in 60 min after the death of rabbits from anoxia, in all the organs of the body. Rapid artificial cooling of the rabbits to 20 degrees C undertaken within 10 min after death preserved nucleic acid biosynthesis and permitted restoration of life 3-4 h after death, with recovery beginning in 60 min. During the reanimation the addition of ATP to the blood stimulated the restoration of RNA biosynthesis in the spinal cord to a considerable extent; the addition of cocarboxylase to the blood promoted cardiac RNA biosynthesis as well as cardiac and pancreatic DNA biosynthesis during recovery.