The demographic data, clinical factors, HD mode, and laboratory parameters were recorded from the medical records. The operational definitions of variables in this study were listed in Table 3-1.
Table 3-1. Operational Definitions of Variables
Variable Operation definition Attribute
Demographics
Age (years old) From the birth day to December 2005 Ratio Gender Male, female. If female, before menopause (1),
menopause (2) Nominal
Education level Nil, elementary school, junior high school, high
school, junior collage, collage, master Nominal Marital status Single, married, separated, widow/widower,
divorced Nominal
Occupation None, part-time, day-time, night-time Nominal Family income
(thousand)
(1)≦30, 30<(2)≦60, 60<(3)≦90, 90<(4)≦120,
120<(5)≦150, 150<(6) Ordinal
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Demographics
Smoking Yes, No Nominal
Yes (pack) (1)≦0.5, 0.5<(2)≦1, 1<(3)≦2, (4)>2 Ordinal
Caffeine Yes, No Nominal
Yes (cup) (1)≦1, 1<(2)≦2, 2<(3)≦3, (4)>3 Ordinal Religion None, Taoism, Buddhism, Christian, Catholic,
Muslim Nominal
Hemodialysis and co-morbidity
Causes of ESRD Diabetes mellitus (DM), Hypertension (HT), Chronic glomerulonephritis (CGN), Systemic lupus erythematous (SLE), polycystic kidney disease (PKD)
Nominal
Co-morbidity DM, HT, angina pectoris, heart failure (HF), myocardial infarction, cerebral vascular accident (CVA), chronic obstructive pulmonary disease (COPD), liver cirrhosis, chronic hepatitis,
peripheral vascular disease, neoplasm, head injury, psychiatry disease
Nominal
Time on dialysis
(years) From the day of first time HD to December 2005 Ratio Hemodialysis (HD)
shift mode HD in the Morning, afternoon, or at night Nominal HD times/per week HD times per week, 1,2,3, >3 Ordinal HD duration
hours/per session HD≦3, 3< HD≦3.5, 3.5< HD≦4, 4< HD Ordinal Clinical parameters and laboratory data
Serum albumin
(g/dl) Pre-HD serum albumin value on December 2005 Ratio Blood urea nitrogen
(BUN) mg/dl Pre-HD serum BUN value on December 2005 Ratio Creatinine (Cr) Pre-HD serum creatinine value on December 2005 Ratio Urea reduction rate
(%)
The percentage of (Pre-HD serum BUN minus
Post-HD BUN)/ Pre-HD serum BUN Ratio
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Clinical parameters and laboratory data
Kt/V (Daugirdas) The Daugirdas method Kt/V = -ln(R-0.008*t) + (4-3.5* R) * UF/W, R=post-HD BUN/Pre-HD BUN, t = HD duration (hours), UF= ultrafiltration volume (Liter), W= Post-HD body weight (Kg), on December 2005
Ratio
Uric acid (mg/dl) Pre-HD serum uric acid value on December 2005 Ratio Total cholesterol
(mg/dl) T-CHO Pre-HD serum cholesterol value on December 2005 Ratio Triglyceride (TG)
(mg/dl)
Pre-HD serum triglyceride value on December
2005 Ratio
Na meq/L Pre-HD serum sodium value on December 2005 Ratio Ca * P Pre-HD serum calcium value multiplier serum
phosphate on December 2005 Ratio
Ferritin (ng/ml) Pre-HD serum Ferritin value on December 2005 Ratio K (meq/L) Pre-HD serum potassium value on December 2005 Ratio iPTH (pg/ml) Pre-HD serum intact parathyroid hormone value on
December 2005 Ratio
Iron (ug/dl) Pre-HD serum iron value on December 2005 Ratio Ca (mg/dl) Pre-HD serum calcium value on December 2005 Ratio GOT (IU/L) Pre-HD serum GOT value on December 2005 Ratio Total iron binding
capacity (TIBC) (ug/dl)
Pre-HD serum TIBC value on December 2005 Ratio P (mg/dl) Pre-HD serum phosphate value on December 2005 Ratio GPT (IU/L) Pre-HD serum GPT value on December 2005 Ratio Red Blood Cell
(*106) Pre-HD red blood cell on December 2005 Ratio Hemoglobin (g/dl) Pre-HD hemoglobin value on December 2005 Ratio Hct (%) Pre-HD Hct value on December 2005 Ratio
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Clinical parameters and laboratory data Weight (Kg) before
HD
The body weight of the patient before HD on
December 2005 Ratio
Weight (Kg) after HD
The body weight of the patient after HD on
December 2005 Ratio
Systolic BP (mmHg)
The systolic blood pressure before HD on
December 2005 Ratio
Diastolic BP (mmHg)
The diastolic blood pressure before HD on
December 2005 Ratio
Respiratory rate
(time/minute) The respiratory rate before HD on December 2005 Ratio Heart rate
(beats/minute)
The heart beats per minute before HD on December
2005 Ratio
Sedatives The kinds of sedatives used by patient, nil, 1,2,3, >3 Ordinal EPO (U/month) The injection dose of erythropoitin per month Ordinal Ferritin supply The injection dose of ferritin per month, nil, 100
mg, 400 mg, > 400mg Ordinal
The Pittsburgh Sleep Quality Index (PSQI)
Time to bed When the patient has usually gone to bed Ratio Time to sleep
(minute) The time the patient need to fall asleep Ratio Time to get up When the patient has usually gotten up in the
morning Ratio
Hours of sleep Hours of actual sleep the patient got at night Ratio Trouble sleeping in
the past month
How often has the patient had trouble sleeping, nil (0), less than once a week (1), once or twice a week
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Have to get up to use the bathroom
Nil (0), less than once a week (1), once or twice a
week (2), three or more times a week (3) Ordinal The Pittsburgh Sleep Quality Index (PSQI)
Cannot breathe
Very good (0), fairly good (1), fairly bad (2), very
bad (3) Ordinal
International Restless Legs Syndrome rating scale (IRLS) RLS discomfort in
patient’s legs or arms
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild (0) None
Ordinal RLS symptoms
need to move
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild (0) None
Ordinal
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
International Restless Legs Syndrome rating scale (IRLS) Relief from moving
around
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild (0) None
Ordinal Sleep disturbance
by RLS symptoms
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild
(0) None Ordinal
Tiredness,
sleepiness by RLS symptoms
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild
(0) None Ordinal
Overall your RLS severity as a whole
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild (0) None
(4) Very severe (This means 8 hours per 24 hour day or more.), (3) Severe (This means 3 to 8 hours per 24 hour day.), (2) Moderate (This means 1 to 3 hours per 24 hour day.), (1) Mild (This means less than 1 hour per 24 hour day.), (0) None
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild (0) None
Ordinal
RLS symptoms on mood
(4) Very severe, (3) Severe, (2) Moderate, (1) Mild,
(0) None Ordinal
Beck Depression Inventory-II (BDI-II)
Sad (0) I do not feel sad.(1) I feel sad. (2) I am sad all the time and I can't snap out of it. (3) I am so sad or unhappy that I can't stand it.
Ordinal Discouraged (0) I am not particularly discouraged about the
future. (1) I feel discouraged about the future. (2) I feel I have nothing to look forward to. (3) I feel that the future is hopeless and that things cannot
improve.
Ordinal
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Beck Depression Inventory-II (BDI-II)
Failure experience (0) I do not feel like a failure. (1) I feel I have failed more than the average person. (2)As I look back on my life, all I can see is a lot of failure. (3) I feel I am a complete failure as a person.
Ordinal
Dissatisfied (0) I get as much satisfaction out of things as I used to. (1) I don't enjoy things the way I used to. (2) I don't get any real satisfaction out of anything anymore. (3) I am dissatisfied with everything the way I used to.
Ordinal
Guilty (0) I don't feel particularly guilty. (1) I feel guilty a good part of the time. (2) I feel quite guilty most of the time. (3) I feel guilty all of the time. disappointed in myself. (2) I am disgusted with myself. (3) I hate myself
Ordinal
Blame (0) I don't feel I am any worse than anybody else. (1) I am critical of myself for my weaknesses or
mistakes. (2) I blame myself all the time for my faults. (3) I blame myself for everything bad that happens.
Ordinal
Suicide (0) I don't have any thoughts of killing myself. (1) I have thoughts of killing myself, but I would not carry them out. (2) I would like to kill myself. (3) I would kill myself if I had the chance.
Ordinal
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Beck Depression Inventory-II (BDI-II)
Irritated (0) I am no more irritated by things than I ever am.
(1) I am slightly more irritated now than usual. (2) I am quite annoyed or irritated a good deal of the time. (3) I feel irritated all the time now.
Ordinal
Lost interest (0) I have not lost interest in other people. (1) I am less interested in other people than I used to be. (2) I have lost most of my interest in other people. (3) I have lost all of my interest in other people.
Ordinal
Make decision (0) I make decisions about as well as I ever could.
(1) I put off making decisions more than I used to.
(2) I have greater difficulty in making decisions than before. (3) I can't make decisions at all anymore.
Ordinal
Valueless (0) I don't feel that I am valueless. (1) I am worried that I am more valueless than before. (2) I feel that am more valueless than another people. (3) I believe that I am completely valueless.
Ordinal
Lost energy (0) I can work about as well as before. (1) It takes an extra effort to get started at doing something. (2) I have to push myself very hard to do anything. (3) I can't do any work at all. long. (3b) I wake up s1-2 hours earlier than I used to and cannot get back to sleep.
Ordinal
Angry (0) I don't get more angry than usual. (1) I get a little bit angry more easily than I used to. (2) I get angry more easily than I used to. (3) I get more angry anytime.
Ordinal
Table 3-1. Operational definitions of variables (cont’)
Variable Operation definition Attribute
Beck Depression Inventory-II (BDI-II)
Appetite (0) My appetite is no change as before. (1a) My appetite is worse as usual. (1b) My appetite is better as usual. (2a) My appetite is much worse as usual.
(2b) My appetite is much better as usual. (3a) I have no appetite at all. (3b) I want to eat foods anytime.
Ordinal
Concentrate on (0) I can concentrate on anything as well as before.
(1) I can concentrate as not well as before. (2) I cannot concentrate on anything for a long time.
(3) I find that I cannot concentrate on anything.
Ordinal
Tired (0) I don't get more tired than usual. (1) I get tired more easily than I used to. (2) I get tired from doing almost anything. (3) I am too tired to do anything.
Ordinal Lost interested in
sex
(0) I have not noticed any recent change in my interest in sex. (1) I am less interested in sex than I used to be. (2) I am much less interested in sex now.
(3) I have lost interested in sex completely.
Ordinal