I want to test whether changes in Hemoglobin (Hgb) levels over time can help diagnose Myelodysplastic syndrome (MDS).
I have a cohort of thousands of patients. Each patient has several Hgb measurements over a period of 3 years. Measurements are unevenly spaced and few (anything from two to 4 measurements).
My questions: 1. Is a time series the correct model for me considering I have so few observation over time for each subject ? if not how do I analyze the trend ? 2. If I should use a time series, I thought of tagging each lab measurement by its year so as to make the measurements evenly spaced (this seems sensible enough from a physiological perspective). Is this valid ? Is there a better way to handle the inequality of measurement spacing ? 3. What do I use to compare trends between two groups ?
I would be most obliged if you could refer me to the appropriate further reading