Patient Characteristics. Overall, 167 participants completed a survey distributed via mail or in clinic. Of the 300 surveys distributed via mail, 125 participants responded (41.7%), including 66 of 150 participants from Mayo Clinic in Minnesota (44.0%), 27 of 75 from Mayo Clinic Arizona (36.0%), and 32 of 75 from Mayo Clinic Florida (42.7%). Of the 122 surveys distributed in clinic at MCR, an additional 42 participants responded (34.4%). Demographics of all 167 participants are outlined in Table 1. Mean participant age was 60.9 (12.7) years, and the median time from KT was 4.0 (1.2–5.4) years. Overall, 55.7% of respondents were male, 84.7% were white, 82% finished some college or obtained a technical degree, 75.2% were married, and 41.2% were retired or unemployed.
Table 1
Demographics of survey respondents
Characteristics of Respondents | N = 167 |
Age (years), mean (range) | 60.9 (21.7–86.1) |
Male, N (%) | 93 (55.7) |
Race, N (%) White Black/African-American Asian American Indian/Alaskan Native Mixed race (more than one race) Other | 138 (84.7) 9 (5.5) 6 (3.7) 4 (2.5) 4 (2.5) 2 (1.2) |
Hispanic/Spanish/Latino ethnicity, N (%) | 7 (4.2) |
Marital status, N (%) Never married Married Living with partner Separated, divorced, widowed | 15 (9.1) 124 (75.2) 7 (4.2) 19 (11.5) |
Education level, N (%) 8th grade or less Some high school High school graduate/GED Some college/technical degree College graduate Advanced degree | 1 (0.6) 1 (0.6) 28 (16.8) 57 (34.1) 50 (29.9) 30 (18.0) |
Work status, N (%) Full-time employed Part-time employed Homemaker Retired or unemployed On disability or leave | 58 (35.2) 15 (9.1) 6 (3.6) 68 (41.2) 18 (10.9) |
Current yearly household income, N (%) Less than $20,000 $20,000 to $29,999 $30,000 to $39,999 $40,000 to $59,999 $60,000 to $79,999 $80,000 to $99,999 $100,000 or more | 16 (10.4) 13 (8.4) 6 (3.9) 23 (14.9) 23 (14.9) 21 (13.6) 52 (33.8) |
Current living situation, N (%) Living in a home Living in an apartment Assisted living/nursing home Homeless Other | 150 (90.4) 11 (6.6) 1 (0.6) 1 (0.6) 3 (1.8) |
Including yourself, current number people residing in your home, N (%) 2 3 4 or more | 92 (60.9) 19 (12.6) 16 (10.6) |
Time from kidney transplant (years), mean (range) | 4.0 (0.3–24.2) |
Donor type, N (%) Deceased Living related Living unrelated | 55 (32.9) 42 (25.1) 70 (41.9) |
Prior kidney transplant, N (%) | 16 (9.6) |
History of pre-transplant dialysis, N (%) | 93 (55.7) |
Cause of end-stage renal disease, N (%) Glomerulonephritis Diabetes Polycystic kidney disease Other or unknown | 48 (28.7) 30 (18.0) 36 (21.6) 53 (31.7) |
Estimated glomerular filtration rate (GFR) (ml/min/1.73 m2), mean (range) | 49.0 (15–90) |
Comorbidities, N (%) Diabetes Hepatitis Glaucoma Depression Asthma Osteoarthritis Hyperlipidemia Hypertension Coronary artery disease Cancer Congestive heart failure Inflammatory arthritis | 51 (30.5) 2 (1.2) 4 (2.4) 38 (22.8) 10 (6.0) 9 (5.4) 117 (70.1) 151 (90.4) 28 (16.8) 39 (23.4) 9 (5.4) 7 (4.2) |
Number of comorbidities, N (%) 2 3 4 or more Median number of conditions | 43 (25.7) 49 (29.3) 48 (28.7) 3.0 |
Number of medications, mean (range) | 11.5 (3.0–21.0) |
Immunosuppression, N (%) Tacrolimus Cyclosporine Belatacept Sirolimus | 150 (89.8) 8 (4.8) 6 (3.6) 3 (1.8) |
Prednisone maintenance, N (%) | 122 (73.1) |
History of acute rejection, N (%) | 40 (24.0) |
Estimated glomerular filtration rate (ml/min/1.73 m2), mean (range) | 49 (15–90) |
Smoking history, N (%) Actively smoking Prior smoker Never smoker | 3 (1.8) 63 (38.0) 100 (60.2) |
Adherence to medications, N (%) Always take all medications Usually take all medications (85% of time) Sometimes take all medications (< 80% of time) | 158 (94.6) 8 (4.8) 1 (0.6) |
How often do you have problems learning about your medical condition because of difficulty understanding written information? N (%) All of the time Most of the time Some of the time Little of the time None of the time | 2 (1.2%) 0 (0.0%) 13 (7.8%) 32 (19.2%) 120 (71.9%) |
How confident are you filling out forms by yourself? N (%) Always Often Sometimes Occasionally Never | 127 (76.0%) 24 (14.4%) 8 (4.8%) 3 (1.8%) 5 (3.0%) |
How often do you have trouble understanding medical information spoken to you by doctors or nurses? N (%) All of the time Most of the time Some of the time Little of the time None of the time | 4 (2.4%) 3 (1.8%) 17 (10.2%) 49 (29.3%) 94 (56.3%) |
Exploratory Factor Analysis (EFA). Scores from the 14 items within the KT-specific supplement are displayed in Table 2. Two items contained large amounts of missing data (≥ 25% of participants responding “does not apply to me”) and were therefore excluded from EFA, in order to produce a stable solution. This included Q9 (“I have felt like I would like to communicate more with my kidney donor or the family of the person who donated my kidney”) and Q10 (“My dialysis graft or fistula [area of arm where needles went during hemodialysis] has bothered me”).
Table 2
Scores from original items within the kidney-transplant specific supplement
Item1 | N | Mean (SD) | Score range | Not Applicable or Missing |
Q1. I have been concerned my KT is losing function | 160 | 2.98 (0.96) | 1.00–4.00 | 7 |
Q2. I have been confident that I am taking good care of my KT | 163 | 1.67 (0.72) | 1.00–4.00 | 4 |
Q3. I have been concerned that I will have to started dialysis in the future | 154 | 3.04 (0.96) | 1.00–4.00 | 13 |
Q4. I have been concerned about my body rejecting my KT | 160 | 2.88 (0.93) | 1.00–4.00 | 7 |
Q5. I have been concerned that my original kidney disease will return and affect the function of my KT | 146 | 2.90 (0.97) | 1.00–4.00 | 21 |
Q6. I have been confident that I will never do anything that will hurt my KT | 163 | 1.79 (0.79) | 1.00–4.00 | 4 |
Q7. I feel responsible for my kidney transplant doing well | 163 | 1.48 (0.57) | 1.00–3.00 | 4 |
Q8. I feel that I know enough about the person who donated my kidney | 156 | 1.79 (1.03) | 1.00–4.00 | 11 |
Q9. I have felt like I would like to communicate more with my kidney donor or the family of the person who donated my kidney | 126 | 2.66 (1.01) | 1.00–4.00 | 41 |
Q10. My dialysis graft or fistula has been bothering me | 76 | 2.92 (1.04) | 1.00–4.00 | 91 |
Q11. I have been concerned about developing an infection of any type | 161 | 2.61 (0.98) | 1.00–4.00 | 6 |
Q12. I have been concerned about developing a cancer of any type | 162 | 2.69 (0.89) | 1.00–4.00 | 5 |
Q13. I have had difficulty taking my anti-rejection medications as directed | 164 | 3.55 (0.72) | 1.00–4.00 | 3 |
Q14. I have been bothered by side effects of my anti-rejection medications | 163 | 2.87 (1.03) | 1.00–4.00 | 4 |
1All items use the following response scale: 1-strongly agree; 2-agree; 3-disagree; 4-strongly disagree; 5-not applicable |
An EFA performed on the remaining 12 items revealed three factors with corresponding eigenvalues of 4.06, 1.85, and 1.07. Examination of the scree plot (not shown) also supported extraction of three factors with an inflection point appearing at the third factor. The three factors were extracted using PAF and accounted for 46% of the total variance. Two items had very low item communalities (h2 < 0.25): “I feel I know enough about the person who donated my kidney” (Q8) and “I have had difficulty taking my anti-rejection medications as directed” (Q13). The decision was made to remove these two items from the factor model based on these low communalities. The EFA was then re-run to obtain the final factor model.
The EFA performed on the remaining 10 items once again revealed three factors, with corresponding eigenvalues of 3.94, 1.73, and 1.01. The three factors extracted using PAF accounted for 53% of the total variance. An oblique promax rotation was used to facilitate interpretation of the loadings of the extracted factors. Factor loadings and item communalities appear in Supplemental Table 2. The first factor included items assessing concern about loss of KT function, return to dialysis, rejection, or recurrent disease (Q1, 3, 4, 5) and was labelled “transplant function.” The second factor included items assessing confidence in one’s ability to take care of the KT and feeling responsible for the KT (Q2, 6, 7) and was labelled “transplant self-management.” The third factor included concern about side effects of immunosuppression (Q11, 12, 14) and was labelled “transplant adverse effects.” Final item communalities ranged from 0.36 to 0.78.
The EFA results supported aggregation of KT-specific items into three domain scales. Standard PETS scoring criteria were used to calculate scale scores for transplant function (4 items), transplant self-management (3 items), and transplant adverse effects (3 items), with scores standardized to a 0-100 scale. Scale scores were derived such that a higher score reflects greater treatment burden, which necessitated prior reverse coding of some items. Spearman’s correlations of each of the three KT-specific scales are displayed in Supplemental Table 3. Mean scale scores of the PETS measure, the newly derived KT-specific scales, and the other measures included in the survey are displayed in Table 3.
Table 3
Responses to PETS, the KT-specific supplement scales, and other surveys
| N | Mean (SD1) | Score range2 |
PETS3 scales |
Medical information | 162 | 17.4 (16.5) | 0.0-71.4 |
Medications | 159 | 13.0 (16.5) | 0.0-92.9 |
Medical appointments | 158 | 15.1 (15.8) | 0.0-58.3 |
Monitoring health | 157 | 22.1 (22.1) | 0.0-100.0 |
Diet | 166 | 32.6 (20.0) | 0.0-100.0 |
Exercise or physical therapy | 166 | 39.8 (24.3) | 0.0-100.0 |
Relationships with others | 164 | 12.1 (16.6) | 0.0-87.5 |
Medical and health care expenses | 162 | 32.3 (24.9) | 0.0-100.0 |
Difficulty with health care services | 156 | 26.8 (19.5) | 0.0-90.5 |
Role/social activity limitations | 162 | 16.2 (20.4) | 0.0-100.0 |
Physical/mental fatigue | 161 | 21.8 (21.3) | 0.0–90.0 |
Bother due to reliance on medicine | 159 | 13.4 (22.5) | 0.0-100.0 |
Bother due to medicine side effects | 159 | 23.9 (28.9) | 0.0-100.0 |
KT-specific supplement scales |
Transplant function | 158 | 35.1 (26.1) | 0.0-100.0 |
Transplant self-management | 164 | 21.7 (18.7) | 0.0-77.8 |
Transplant adverse effects | 162 | 42.6 (24.8) | 0.0-100.0 |
PROMIS Global-104 |
Global Physical Health | 156 | 49.9 (8.8) | 26.7–67.7 |
Global Mental Health | 164 | 50.0 (9.0) | 21.2–67.6 |
KDQOL-SF5 |
Burden of kidney disease | 165 | 77.5 (23.6) | 0.0-100.0 |
Symptoms/problems of kidney disease | 166 | 85.6 (13.6) | 25.0-100.0 |
Effects of kidney disease | 166 | 85.9 (16.5) | 6.3–100.0 |
TSQM6 |
Side effects | 158 | 80.1 (26.8) | 0.0-100.0 |
Convenience | 81 | 81.2 (18.0) | 22.2–100.0 |
PMCSM7 |
Self-Management | 166 | 33.7 (6.0) | 14.0–40.0 |
1Standard deviation; 2Scores for surveys range from 0 (lowest) to 100 (highest) with PMCSM ranging from 8 (lowest) to 40 (highest); 3Patient Experience with Treatment and Self-Management; 4Patient-Reported Outcomes Measurement Information System (T-Score); 5Kidney Disease Quality of Life Short-Form; 6Treatment Satisfaction Questionnaire for Medication; 7Perceived Medical Condition Self-Management Scale |
Reliability, construct validity, and known-groups validity. Internal reliabilities for the three KT-specific supplement scales were the following: Cronbach’s α = 0.83 for the transplant function scale, alpha = 0.72 for the transplant self-management scale, and alpha = 0.66 for the transplant adverse effects scale. In terms of construct validity, all three scales of the KT-specific supplement were positively and significantly correlated with the treatment burden scores of the PETS scales (Supplemental Table 4). Higher scores on the transplant function scale were most strongly correlated with higher burden on the medical and healthcare expenses scale of the PETS (ρ = 0.36), higher scores on the transplant self-management scale were most strongly correlated with higher burden on the monitoring health scale of the PETS (ρ = 0.47), and higher scores on the transplant adverse effects scale were most strongly correlated with higher burden on the medication side effects bother scale of the PETS (ρ = 0.52). We observed that scores on the KT-specific supplement transplant function scale (35.1 ± 26.1) were higher than scores on the PETS monitoring health (22.1 ± 22.1) and physical/mental fatigue scales (21.8 ± 21.3). Likewise, scores on the KT-specific transplant adverse effects scale (42.6 ± 24.8) were higher than scores on the medications scale (13.0 ± 16.5), the bother related to medication reliance scale (13.4 ± 22.5), and the bother related to medicine side effects scale (23.9 ± 28.9) of the PETS.
Similarly, higher scores on the KT-specific supplement scales were associated with scores on measures of general physical and mental wellbeing, kidney disease-specific quality of life, medication satisfaction, and self-efficacy (Supplemental Table 5). Higher scores on the KT-specific supplement scales were significantly correlated with worse physical and mental health (PROMIS-10); worse burden, symptoms/problems, and effects of kidney disease (KDQOL-SF); more bother due to medication side effects (TSQM side effects); and lower self-efficacy for managing chronic illness (PMCSM). Most of the correlations (86%) were of medium size or greater (ρ ≥ 0.30) supporting construct validity of the KT-specific supplement scales.
Scores on the KT-specific supplement scales were also compared across groups of patients to assess known-groups validity (Supplemental Table 6). We found that patients with diabetes, patients with more comorbidities, patients taking more medications, and patients transplanted > 1 year ago had significantly higher burden scores on the transplant self-management scale. Patients with an eGFR < 30 ml/min/1.73 m2 had significantly higher burden scores on the transplant function scale and a trend toward significantly higher burden scores on the transplant adverse effects scale (54.2 ± 29.7 versus 32.1 ± 24.6, p = 0.004 and 54.9 ± 30.5 versus 41.6 ± 23.6, p = 0.07, respectively).