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Keywords:

  • quality of life;
  • questionnaire;
  • renal cell cancer;
  • general population;
  • patient-reported outcome

Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES

BACKGROUND:

Metastatic renal cell cancer is associated with poor long-term survival and has no cure. Traditional clinical endpoints are best supplemented by patient-reported outcomes designed to assess symptoms and function. Normative data was obtained on the National Comprehensive Cancer Network-Functional Assessment of Cancer Therapy–Kidney Symptom Index (NFKSI) to aid in score interpretation and planning of future trials.

METHODS:

General population data were obtained from 2000 respondents, who completed the 19-item NFKSI-19, as well the SF-36 (Short Form 36-item instrument) and the PROMIS-29 (29-item Patient Reported Outcomes Measurement Information System), both general health status measures. Basic demographic and self-reported comorbidity data were also collected.

RESULTS:

The sample was 50% female, 85.7% caucasian, with an equal distribution across age bands from 18 years to 75 years and older. Most respondents (62.8%) had more than a high school education and reported an Eastern Cooperative Oncology Group performance status of normal activity without symptoms (63.4%). Score distributions on the NFKSI-19, its subscales, and individual items are summarized.

CONCLUSIONS:

The NFKSI-19 and its subscales now have scores for the general US population, allowing comparability to generic questionnaires such as the SF-36 and PROMIS-29. These data can be used to guide treatment expectations and plan future comparative effectiveness research using the scales. Cancer 2013. © 2012 American Cancer Society.

Although there are new, effective agents in the treatment of metastatic renal cell cancer, it is still associated with poor long-term survival and has no cure. The disease and its treatment can have significant impact on a patient, making relief of symptoms and maintenance of function key goals of any medical intervention.1, 2 Traditional endpoints in clinical oncology, such as patient survival and tumor response, are important, but must be supplemented by patient-reported outcomes (PROs) designed to assess symptoms and function. One such PRO measure is the Functional Assessment of Cancer Therapy–Kidney Symptom Index (FKSI).3

The 15-item FKSI (FKSI-15)3 and its 9-item subset of disease-related symptoms (FKSI-DRS)4 were originally developed with input from patients with kidney cancer and from clinical experts,5 who prioritized important symptoms and concerns.6 We recently sought to further verify adequate coverage of items to address regulatory guidance on the development of patient-reported outcomes.7 To do so, we solicited open-ended input from patients with advanced kidney cancer. Participants' responses in that study were used to modify the original FKSI instrument to produce the National Comprehensive Cancer Network FKSI-19 (NFKSI-19), assessing symptoms of importance to patients with advanced kidney cancer.8 The NFKSI-19 contains all of the items of the original FKSI-15 and the FKSI-DRS. Open-ended patient input as part of the NFKSI-19 development resulted in the addition to the assessment of items on weakness, nausea, diarrhea, and being content with quality of life (Table 1).

Table 1. FKSI Item Content and Descriptive Statistics (N = 2000)
Item ContentFKSI-15?NFKSI- DRS-13?FKSI- DRS-9?MeanaSD
  • a

    These are not raw data values; some items have been reverse-scored per FACIT convention so that higher scores indicate better outcomes.

  • All items in Table 1 comprise the NFKSI-19. Specific items administered as part of other FKSI scales are indicated.

  • Abbreviations: DRS, disease-related symptoms; FKSI, Functional Assessment of Cancer Therapy–Kidney Symptom Index; SD, standard deviation.

I have a lack of energyYesYesYes2.641.18
I have painYesYesYes2.711.24
I am losing weightYesYesYes3.470.89
I feel fatiguedYesYesYes2.741.20
I have been short of breathYesYesYes3.321.00
I am bothered by feversYesYesYes3.850.55
I have bone painYesYesYes3.451.03
I have been coughingYesYesYes3.950.98
I feel weak all overNoYesNo3.460.97
I have had blood in my urineYesYesYes3.910.45
I worry that my condition will get worseYesYesNo3.271.14
I have a good appetiteYesYesNo2.681.22
I am sleeping wellYesYesNo2.081.27
I have nauseaNoNoNo3.740.68
I have diarrheaNoNoNo3.690.55
I am bothered by side effects of treatmentYesNoNo3.680.83
I am able to work (include work at home)YesNoNo2.621.49
I am able to enjoy lifeYesNoNo2.741.52
I am content with the quality of my life right nowNoNoNo2.301.31

Currently, FKSI scores can be used, for example, to compare groups within a cross-sectional study or to compare outcomes between randomized groups in a clinical trial. However, scores obtained in any given study are not easily referenced to a larger population due to a lack of normative data. External reference data on the same instrument in larger samples can place the results of a specific study in context. To that end, the objective of the present project was to obtain general population reference values for the FKSI to aid in the interpretation and understanding of clinical research data.

We present normative data for the FKSI based on data from a sample of the general US adult population. These norms enhance the usefulness and interpretability of the FKSI by allowing scores obtained by patients to be compared to those of a reference group, by offering data on the distribution of scores, and through use of T-scores, allowing comparisons of scores measured on different scales. Furthermore, normative data for the general population on the FKSI allows for calculation of standardized effect sizes, which facilitate comparisons of effect sizes across studies.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES

Participant Recruitment and Survey Administration

We contracted with an Internet panel company, Toluna/Greenfield, for participant recruitment and data collection. Toluna/Greenfield maintains 33 actively managed proprietary panel communities around the world, exclusively for marketing and opinion research. Members are recruited from a broad array of online and offline approaches that best represent the online community as a whole in each country.

Toluna/Greenfield employs several procedures to confirm the identity of their panelists, some of which are outlined below. At registration, a user's e-mail must be both valid and unique within the panel. In addition, the US panel is checked regularly against third-party databases for the verification of the existence of the panelist at the address used at enrollment. The company also regularly runs consistency checks between the basic registration data given and ongoing profiling data, and they include questions in profiling questionnaires to identify inconsistencies in responses.

Toluna/Greenfield sent e-mail invitations to eligible panel members from among its 536,000 US members in order to obtain data from 2000 participants. Panelists were given a link that took them to a secure Web site where the survey was administered, after they provided consent. Participants' survey responses cannot be linked in any way to any identifying information.

Measures

Participants completed the NFKSI-19, the SF-36 (Short Form 36, version 2), the 29-item Patient Reported Outcomes Measurement Information System (PROMIS-29) instrument, as well as a brief set of demographic questions and items asking about self-reported chronic conditions.

The NFKSI-19 is described above and in a recent publication (see Table 1 for item content).8 From the NFKSI-19, one can derive scores for the original 15-item FKSI (FKSI-15), the original 9-item Disease-Related Symptoms Scale (FKSI-DRS-9), and the expanded 13-item Disease-Related Symptoms Scale (NFKSI-DRS-13) drawn from the NFKSI-19. (A 12-item DRS focused on physical symptoms can also be derived.) Higher scores are better; lower scores indicate a more symptomatic respondent. The NFKSI-19 and scoring instructions can be found at www.facit.org.

The SF-36, version 2,9 is one of the most widely used general measures of health status. The 36-item instrument provides a profile of 8 health subscale scores and 2 aggregate higher order scores from these 8 subscales, the physical component summary and mental component summary, which explain 80% to 85% of the reliable variance. Higher scores represent better health-related quality of life.

The Patient Reported Outcomes Measurement Information System (PROMIS) network (www.nihpromis.org) developed several profile measures, such as the PROMIS-29, which assesses fatigue, depression, anxiety, sleep, physical function, social function, and pain (intensity and interference with function).10 Norm-based scores are available so that scores of 50 ± 10 represent the mean ± standard deviation of the general population. Higher scores on the symptom-oriented domains indicate worse symptoms, and higher scores on the function-oriented domains indicate better functioning.

Sample

Data collection occurred in fall 2011. A total of 2000 participants were successfully surveyed from the Internet panel of the general population. We established quotas by sex and age (Table 2), leading to an equal sex split and equal age bands of 18-29, 30-44, 45-59, 60-74, and 75 years of age and older. Our sample was primarily non-Hispanic (94.5%), white (85.7%), and married (46.8%). Many respondents had some college or a technical degree (41.9%), and more than half had an income of less than $40,000. Most respondents reported that they had normal activity without symptoms (63.4%), although, notably, 30.8% indicated experiencing symptoms that did not require bed rest during the waking day.

Table 2. General US Population Sample (N = 2000)
Characteristicn%
  • a

    Participants could endorse more than 1 race.

  • Abbreviation: ECOG, Eastern Cooperative Oncology Group.

Sex  
 Female100050.0
 Male100050.0
Age, y  
 18-2940020.0
 30-4440020.0
 45-5940020.0
 60-7440020.0
 75+40020.0
Ethnicity  
 Hispanic1105.5
 Non-Hispanic189094.5
Racea  
 White171385.7
 Black or African American1608.0
 American Indian/Alaska Native341.7
 Asian743.7
 Native Hawaiian or other Pacific Islander50.3
 Other552.8
Marital status  
 Never married40120.1
 Married93546.8
 In committed relationship1899.5
 Separated442.2
 Divorced23111.6
 Widowed20010.0
Education  
 <High school grad/GED683.6
 High school grad/GED50125.1
 Some college/technical degree/AA83741.9
 College degree (BA/BS)41820.9
 Advanced degree (MA, MS, MBA,  PhD, MD, JD)1768.8
Patient ECOG performance status  
 I have normal activity without symptoms126863.4
 I have some symptoms but do  not require bed rest during the waking day61530.8
 I require bed rest for less than 50% of the  waking day874.4
 I require bed rest for more than 50% of the  waking day251.3
 I am unable to get out of bed50.3

We polled respondents regarding specific health conditions, using an investigator-developed checklist. A summary of those data is provided in Table 3. Many respondents (22.4%) reported no comorbid conditions, and just more than one-third (34.7%) reported 1 or 2 comorbid conditions. The most common conditions endorsed were rheumatism (eg, arthritis; n = 628) and depression (n = 503).

Table 3. Prevalence of Comorbid Conditions
 N%
  1. Abbreviations: AIDS, acquired immune deficiency syndrome; COPD, chronic obstructive pulmonary disease; HIV, human immunodeficiency virus.

Total number of comorbid conditions  
 044822.4
 1-269434.7
 325712.9
 4+60130.1
Frequency of specific conditions  
 Hypertension89544.8
 Rheumatism62831.4
 Depression50325.2
 Anxiety40020.0
 Diabetes34217.1
 Migraines32716.4
 Asthma29614.8
 Osteoarthritis28014.0
 Sleep disorder27513.8
 COPD20810.4
 Angina1939.7
 Cancer1718.6
 Heart attack (myocardial infarction)1216.1
 Alcohol or drug problem1216.1
 Coronary artery disease1155.8
 Heart failure/congestive heart failure1095.5
 Liver disease, hepatitis, or cirrhosis954.8
 Stroke or transient ischemic attack924.6
 Kidney disease703.5
 Multiple sclerosis180.9
 HIV or AIDS150.8

Data Analysis

Responses on the FKSI were scored using the standard FACT (Functional Assessment of Cancer Therapy) scoring methodology. If > 50% of items were completed, the FKSI scores were calculated as the sum of the item responses divided by the number of items completed multiplied by the total number of items in the scale (eg, 19 in the case of the NFKSI-19). If fewer than 50% of the items were completed, the scores were considered missing.

Within each age and sex subgroup, on the FKSI, we calculated mean, standard deviation, percentage scoring the lowest possible score, percentage scoring the highest possible score, the lowest and highest observed scores, and 25th, 50th (median), and 75th percentiles.

We also assessed how well our sample represented the US population by comparing the age, sex, and race to data from the 2000 US Census. We identified a subset of our sample that matched the demographic profile of the general US population, using disproportionate sampling (“raking”) in the manner applied by Liu et al.11 Descriptive statistics of the FKSI scores were recalculated for this subset; these data are not presented here but are available from the authors.

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES

Table 4 presents normative general population scores across the total sample and by sex for the NFKSI-19 and its subscales. (Normative scores by age band are available upon request.) The NFKSI-19 (range = 0-76) had a median value of 62 and mean of 59.8 (standard deviation [SD] = 11.2). The FKSI-15 (range = 0-60) had a median value of 48 and a mean of 46.6 (SD = 9). The NFKSI-DRS-13 (range = 0-52) had a median value of 43 and a mean of 41.0 (SD = 8). Finally, the FKSI-DRS-9 (range = 0-36) had a median value of 31 and a mean of 29.5 (SD = 5.6). Table 1 shows individual item statistics.

Table 4. Normative Data of General US Adult Population
 NFKSI-19 Range, 0-76FKSI-15 Range, 0-60NFKSI-DRS-13 Range, 0-52FKSI-DRS-9 Range, 0-36
  1. Abbreviations: DRS, disease-related symptoms; FKSI, Functional Assessment of Cancer Therapy–Kidney Symptom Index; NFKSI, National Comprehensive Cancer Network FKSI; SD, standard deviation.

Total Sample (N = 2000)
 Mean59.846.641.029.5
 Standard deviation11.29.08.05.6
 Percent at floor0.00.00.00.1
 Percent at ceiling2.52.93.4510.3
 Minimum observed score13.010.05.00
  25th Percentile54.041.037.027.0
  50th Percentile (median)62.048.043.031.0
  75th Percentile68.053.047.034.0
 Maximum observed score76.060.052.036.0
Males (N = 1000)
 Mean59.746.641.129.7
 Standard deviation11.29.08.05.8
 Percent at floor0.00.00.00.0
 Percent at ceiling2.63.33.913.3
 Minimum observed score13.010.05.01.0
  25th Percentile54.041.037.027.0
  50th Percentile (median)62.048.043.031.0
  75th Percentile68.053.047.034.0
 Maximum observed score76.060.052.036.0
Females (N = 1000)
 Mean59.846.540.829.3
 Standard deviation11.29.08.05.5
 Percent at floor0.00.00.00.2
 Percent at ceiling2.42.53.07.2
 Minimum observed score16.012.08.00
  25th Percentile53.541.036.026.0
  50th Percentile (median)62.048.043.031.0
  75th Percentile68.054.047.033.0
 Maximum observed score76.060.052.036.0

Respondents also completed the SF-36 version 2 and the PROMIS-29 instruments. As seen in Table 5, scores on the SF-36 mental and physical summary components as well as the PROMIS physical function, anxiety, depression, fatigue, sleep disturbance, satisfaction with social role, and the pain interference scales were quite comparable to the respective normative data for those scales. Symptom reports on the FKSI scales were significantly correlated with the SF-36 and PROMIS-29 scales (Spearman correlations = 0.49-0.72), suggesting that although there is shared variance between the FKSI and the general measures, the FKSI scales also measure unique aspects of symptom experience.

Table 5. General Health-Related Quality of Life (N = 2000)a
 Mean (SD)Median
  • a

    Except for pain intensity, all scores standardized to mean (standard deviation [SD]) = 50 (10), based on respective normative samples. Pain intensity score, based on a single 0 to 10 rating, was not transformed.

  • Abbreviations: PROMIS-29, 29-item Patient Reported Outcomes Measurement Information System instrument; SF-36, Short Form 36.

SF-36 version 2 scores (standardized)  
 Mental component summary47.7 (12.3)50.8
 Physical component summary46.1 (11.2)48.6
PROMIS-29 scores (standardized)  
 Physical function50.5 (10.0)49.0
 Anxiety50.1 (10.3)48.9
 Depression47.3 (9.7)46.4
 Fatigue47.9 (9.2)48.1
 Sleep disturbance52.0 (10.0)52.4
 Satisfaction with social role49.3 (10.1)49.9
 Pain disturbance49.2 (9.2)49.6
 Pain intensity3.0 (2.6) 2.0

We designed our study to purposefully sample for an equal split by sex and across specified age bands. We also reviewed FKSI scores after defining a subset of 1247 from the total sample of 2000 individuals that approximated age and sex percentages from the 2000 US Census figures.11 We found no meaningful differences between the complete sample and the Census-based subsample (n = 1247) on FKSI, SF-36, or PROMIS averages. Most score differences were on the order of 1 point or less.

Many of our respondents reported having at least 1 chronic or comorbid medical condition. To provide a theoretical upper bound for FKSI scores, Table 6 summarizes total FKSI and FKSI-DRS scores for the sample of 448 respondents who reported no comorbid medical conditions, the 140 respondents who reported having only hypertension, and the combined group (n = 588) of individuals we expected would be a relatively healthy US sample without a major medical condition. As expected, these scores were higher (better) than those derived from the entire sample, which included people with 1 or more diagnosed diseases or disorders.

Table 6. Normative Data for Respondents With No Comorbidities or Hypertension Only
 NFKSI-19 Range, 0-76FKSI-15 Range, 0-60NFKSI-DRS-13 Range, 0-52FKSI-DRS-9 Range, 0-36
  1. Abbreviations: DRS, disease-related symptoms; FKSI, Functional Assessment of Cancer Therapy–Kidney Symptom Index; NFKSI, National Comprehensive Cancer Network FKSI.

No medical comorbidities or chronic conditions (n = 448)
 Mean65.651.345.232.6
 Standard deviation7.86.45.33.8
 Minimum observed score35.028.020.014.0
 25th Percentile61.048.043.031.0
 50th Percentile (median)67.553.046.034.0
 75th Percentile71.056.049.035.0
 Maximum observed score76.060.052.036.0
Hypertension only (n = 140)
 Mean66.051.545.332.5
 Standard deviation6.95.94.83.2
 Minimum observed score44.034.028.021.0
 25th Percentile63.049.043.031.0
 50th Percentile (median)66.552.046.033.0
 75th Percentile71.056.049.035.0
 Maximum observed score76.060.052.036.0
No medical comorbidities or chronic conditions or hypertension (n = 588)
 Mean65.751.445.232.6
 Standard deviation7.66.35.23.6
 Minimum observed score35.028.020.014.0
 25th Percentile62.048.043.031.0
 50th Percentile (median)67.052.046.034.0
 75th Percentile71.056.049.035.0
 Maximum observed score76.060.052.036.0

To facilitate comparisons of patient data to these general population scores, we have included a T-score look-up table (Table 7) for the NFKSI subscales, using data from our complete normative group (N = 2000). The T-score is a linear conversion of the raw scores using the following equation: T-score = ([raw score − raw score mean]/raw score SD) × 10 + 50.

Table 7. T-Score Conversion Table for the General US Adult Population (N = 2000)
NFKSI-19FKSI-15NFKSI-DRS-13FKSI-DRS-9
Raw ScoreT-ScoreRaw ScoreT-ScoreRaw ScoreT-ScoreRaw ScoreT-Score
  1. Abbreviations: DRS, disease-related symptoms; FKSI, Functional Assessment of Cancer Therapy–Kidney Symptom Index; NFKSI, National Comprehensive Cancer Network FKSI.

0–3.40–1.80–1.30–2.5
1–2.51–0.710.01–0.7
2–1.620.421.321.1
3–0.731.532.532.9
40.242.643.844.7
51.153.755.056.4
62.064.866.368.2
72.976.077.5710.0
83.887.188.8811.8
94.698.2910.0913.6
105.5109.31011.31015.3
116.41110.41112.51117.1
127.31211.51213.81218.9
138.21312.61315.01320.7
149.11413.81416.31422.5
1510.01514.91517.51524.2
1610.91616.01618.81626.0
1711.81717.11720.01727.8
1812.71818.21821.31829.6
1913.61919.31922.51931.4
2014.52020.42023.82033.1
2115.42121.52125.02134.9
2216.32222.72226.32236.7
2317.22323.82327.52338.5
2418.12424.92428.82440.2
2518.92526.02530.02542.0
2619.82627.12631.32643.8
2720.72728.22732.52745.6
2821.62829.32833.82847.4
2922.52930.52935.02949.1
3023.43031.63036.33050.9
3124.33132.73137.53152.7
3225.23233.83238.83254.5
3326.13334.93340.03356.3
3427.03436.03441.33458.0
3527.93537.13542.53559.8
3628.83638.33643.83661.6
3729.73739.43745.0  
3830.63840.53846.3  
3931.53941.63947.5  
4032.44042.74048.8  
4133.24143.84150.0  
4234.14244.94251.3  
4335.04346.04352.5  
4435.94447.24453.8  
4536.84548.34555.0  
4637.74649.44656.3  
4738.64750.54757.5  
4839.54851.64858.8  
4940.44952.74960.0  
5041.35053.85061.3  
5142.25155.05162.5  
5243.15256.15263.8  
5344.05357.2    
5444.95458.3    
5545.85559.4    
5646.65660.5    
5747.55761.6    
5848.45862.8    
5949.35963.9    
6050.26065.0    
6151.1      
6252.0      
6352.9      
6453.8      
6554.7      
6655.6      
6756.5      
6857.4      
6958.3      
7059.2      
7160.1      
7260.9      
7361.8      
7462.7      
7563.6      
7664.5      

Differences in FKSI scale scores across categories of patient-reported Eastern Cooperative Oncology Group (ECOG) performance status and number of comorbid conditions are presented in Table 8. Differences in scores across the scales were statistically significant (P < .0001) between adjacent categories in almost all cases. The only exceptions were between the 2 worst categories of ECOG performance status, which were rated similarly across the summary measures.

Table 8. FKSI Comparisons by ECOG Performance Status and Number of Comorbid Conditions
 NFKSI-19FKSI-15NFKSI-DRS-13FKSI-DRS-9
 nMSDPaMSDPaMSDPaMSDPa
  • a

    P values are tests for differences between adjacent categories.

  • Abbreviations: DRS, disease-related symptoms; ECOG, Eastern Cooperative Oncology Group; FKSI, Functional Assessment of Cancer Therapy–Kidney Symptom Index; M, mean; NFKSI, National Comprehensive Cancer Network FKSI; SD, standard deviation.

ECOG             
I have normal activity without symptoms126863.79.0<.000149.87.2<.000143.76.3<.000131.44.6<.0001
I have some symptoms but do not require bed rest during the waking day61554.410.6<.000142.08.5<.000137.17.8<.00126.85.5<.0001
I require bed rest for less than 50% of the waking day8745.411.7.6635.29.3.7731.38.6.8523.26.1.76
I require bed rest for more than 50% of the waking day2544.412.3 34.79.4 31.68.8 23.56.3 
Comorbid Conditions             
 044865.67.8.000251.36.4.000145.25.3<.000132.63.8<.0001
 1-269463.48.6<.000149.56.9<.000143.66.0<.000131.24.2<.0001
 325758.98.9<.000145.87.2<.000140.66.4<.000129.24.4<.0001
 4+60151.612.0 39.99.5 35.08.6 25.36.2 

DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES

We have presented normative data for the FKSI and related symptom indexes, which can be useful for planning trials and for interpreting data from clinical trials that use the scale. In this article, we provide general population normative data for the NFKSI and its derivatives, which will aid in the interpretation of future clinical and research data that use these scales. We also provide validity data to show that in the general population, symptom severity increases with worsening ECOG performance status and with increased medical comorbidity. FKSI scores also measure aspects of health-related quality of life that are not assessed by the SF-36 or PROMIS-29, such as nausea, diarrhea, bone pain, and being bothered by fevers.

We provide raw score distributions for our general population FKSI data and also provide a convenient look-up table to convert raw score values to the T-score metric. T-scores have the advantage of being easy to use and interpret (M = 50, SD = 10) and can facilitate comparisons with other scales when placed on the same metric. A difference in T-scores of one-half standard deviation, or 5 points on the T-score template can be interpreted as likely to reflect a meaningful difference, with the understanding that the minimally important difference is likely less than 5 points.12 For example, if the mean raw score for a patient sample corresponds to a T-score < 45 or > 55, one might conclude that the patient sample symptoms are meaningfully different from those in the general US population. Our sample was drawn from an online panel similar to the US general population on several demographic characteristics, but future testing should address the generalizability of such data to individuals who do not have Internet access.

A review of recent findings may be useful for illustration purposes. For example, Cella et al2 investigated the health-related quality of life from a phase 3 trial of 750 patients with metastatic renal cell carcinoma, randomized to either first-line oral sunitinib or subcutaneous interferon-α. The model mean of postbaseline assessments on the primary symptom endpoint, the FKSI-DRS, indicated that patients on sunitinib fared better than those on interferon-α (29.9 vs 27.53, raw scale). Referencing Table 7, one can also appreciate that although there were mean differences between treatment arms, they are also within a half standard deviation of the general population mean (ie, they were not extremely symptomatic). In another study, Cella and colleagues,13 evaluated the effect of second-line axinitib versus sorafenib on kidney-cancer–specific symptoms and functioning as part of an open-label, randomized phase 3 trial of 723 patients with metastatic renal cell carcinoma. The mean overall postbaseline scores were not significantly different between the axitinib arm versus the sorafenib arm on the FKSI-15 (42.2 vs 41.9; least squares mean) or the FKSI-DRS (28.6 vs 28.4; least squares mean). The FKSI-15 scores of patients in this trial were meaningfully different than the general population norms, at just over half of a standard deviation of the population mean, and the patients' FKSI-DRS subscale scores were within one-third standard deviation of the general population mean (ie, comparable to the general population).

This is the first available general population data for the NFKSI-19 and its subscales. Although the symptoms assessed on the FKSI scales are common in patients with renal cell carcinoma, this study illustrates that the questions asked in the FKSI are potentially applicable to all individuals, with or without a medical condition. They are symptoms experienced to some degree in the general population. These data can be used to guide treatment expectations; in some cases, maintaining patient NFKSI scores at a stable level may be more realistic than expecting improvement, especially in areas where patients are similar to the general population at trial onset. In this report, we summarized general population normative data for the FKSI that should be useful in guiding future comparative effectiveness research using the scales.

CONFLICT OF INTEREST DISCLOSURE

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES

Pfizer paid Northwestern University for the scientific and consultative expertise of Zeeshan Butt, John Peipert, Kimberly Webster, and David Cella in connection with the development of this manuscript. Zeeshan Butt was also supported in part by grant KL2RR025740 from the National Center for Research Resources (National Institutes of Health). Connie Chen is an employee and stockholder of Pfizer. The authors made no additional financial disclosures related to this manuscript.

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. FUNDING SOURCES
  7. CONFLICT OF INTEREST DISCLOSURE
  8. REFERENCES
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