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  • 1. Evaluation of Patients with Advanced Cancer Using the Karnofsky Performance Status JEROME W. YATES, MD, BRUCE CHALMER, MS, F. PATRICK McKEGNEY, MD The Karnofsky Performance Status Scale (KPS) was designed to measure the level of patient activity and medical care requirements. It is a general measure of patient independence and has been widely used as a general assessment of patients with cancer. Although there is a long history of use of the KPS for judging cancer patients, its reliability and validity have been assumed without formal investigation. The interrater reliability of the KPS was investigated in two ways, both of which gave evidence of moder- ately high reliability. The patients evaluated in their home were usually assigned a lower KPS score com- pared with a similar evaluation at the same time done in the outpatient clinic. Construct validity of the KPS was demonstrated by strong correlation with several variables relating to physical function. On- study KPS scores accurately predicted early death, but high initial KPS scores did not necessarily predict long survival. Patient deterioration with subsequent death within a few months could be predicted to a limited extent by a rapidly dropping KPS. These results suggest that the KPS has considerable validity as a global indicator of the functional status of patients with cancer and might be helpful for following other patients with chronic disease. Cancer 45:2220-2224, 1980.W I T H T H E INCREASE in clinical trials designed to evaluate chemotherapeutic agents in the treat-ment of cancer, it became evident that some method Methods A group of patients with advanced cancer, all of whom were being followed as part of the Cancerof quantifying patients’ status relative to degree of in- Rehabilitation Project at the Vermont Regional Cancerdependence in carrying out normal activities and self- Center, were assigned KPS scores at the time of theircare was needed. In 1948, Karnofsky and Burchena15 admission to the project.6 One criterion for admissiondescribed a numerical scale for this purpose. This has to the study was a probable survival of three monthssubsequently become known as the Karnofsky Per- to one year. The KPS scale as used is shown in Table 1 .formance Status Scale (KPS). Although the KPS is The reliability of the KPS was evaluated two ways.widely used for assessment of patients with cancer, First, scores were assigned to each patient by a nurseits reliability and validity have generally been assumed and a social worker independent of each other. Duringwithout formal investigation. In this paper we evaluate the course of the nurses’ training, simultaneous, in-the reliability and validity of the KPS and its usefulness dependent ratings of the same patients by nurses andas a clinical tool. physicians proved to be virtually identical; we won- An earlier study from this institution of patients on dered if this finding would hold for patients evaluatedchronic hemodialysis demonstrated lower performance at nearly, but not exactly, the same time, by otherscores for patients when seen in the home as com- project professionals most directly concerned withpared with the clinic.3 The conclusion was that a more evaluating the patients’ status. Both the nurse’s ratingrealistic appraisal of activity was possible in the home. and the social worker’s rating were based on contactConcurrent home and clinic evaluations were planned with the patient either in the clinic or hospital. Second,as a part of this study. because part of the project involved periodic home visits by the social workers to collect research data, it From the Vermont Regional Cancer Center and the Departments was possible to obtain KPS scores based on contactof Medicine, Epidemiology and Psychiatry, College of Medicine,University of Vermont. with the patients in their home environment. The home This work was supported by NCI grant R18 17868. scores could then be compared with the clinic scores Address for reprints: Jerome Yates, MD, Vermont Regional as a further check on reliability, provided the twoCancer Center, The University of Vermont College of Medicine,Burlington, VT 05401. scores were sufficiently close in time. We considered Accepted for publication May 2, 1979. a difference of one week or less to be sufficiently 0008-543X/80/0415/2220 $0.75 0 American Cancer Society 2220
  • 2. No. 8 USING EVALUATION PATIENTS OF THE KPS . Yates et al. 222 1close for comparison. There were 52 patients for whom TABLR Karnofsky Performance Status Scale 1.two clinic (or hospital) ratings within one week of each 100 Normal, no complaints, no evidence of diseaseother were available, and 50 for whom one clinic rating 90 Able to carry on normal activity, minor signs or symptomsand one home rating within one week of each other of disease 80 Normal activity with effort, some signs or symptoms of diseasewere available. 70 Cares for self. Unable to carry on normal activity or to do In addition t o the KPS, data on a number of other active workvariables relating to both physical and psychological 60 Requires occasional assistance, but is able to care for most of his needsstatus were collected for each patient by the social 50 Requires considerable assistance and frequent medical careworker through a structured interview. Questions con- 40 Disabled, requires special care and assistancecerning satisfaction, happiness, and affect were used in 30 Severely disabled, hospitalization is indicated although death not imminentan attempt to elicit the patient’s own views of various 20 Hospitalization necessary, very sick, active supportiveaspects of their “quality of life.”1-2~4 interview The treatment necessaryformat was evolved locally from results of several 10 Moribund, fatal processes progressing rapidly 0 Deadearlier versions. The two affect variables (positiveand negative) were slightly modified versions of scalesdeveloped by Bradburn based on his model of thestructure of psychological well-being.2 The Pearson TABLE . Variables used in Validity Analysis 2correlations between the KPS and these additional -~variables were used to examine the construct validity Name Descriptionof the KPS. For the purpose of this analysis, data 1. Desire for food “How has your desire for food been in thetaken from all patients on the project in a single month past few days?”(April 1978) were used (a total of 52 patients). The ad- 2. Sleep “How well have you been sleeping in the past few nights?” (3-point scale: well, so-so,ditional variables were described in Table 2. or poorly) Finally for those patients who died during the course 3. Difficulty with “Have you been having any difficultyof the project (N = 104), it was possible t o evaluate the balance keeping your balance in the past fewdegree to which the KPS was correlated with duration days?” (YesiNo) 4. Difficulty on “Have you been having any difficulty goingof survival. This evaluation was made in terms of both stairs up and down stairs in the past few days?”the degree to which initial KPS scores were predictive (YesiNo)of duration of survival (for all 104 patients) and the 5. Pain level “If zero is no pain at all, and 100 is more pain than you could stand, what is yourdegree to which successive KPS scores over time present level of pain?”reflect the course of patients’ diseases. 6 . Happiness “Taken all together, how would you say Characteristics of the patient samples used in this things are these days-would you say that you are very happy, pretty happy, orpaper are given in Table 3. Although there was con- not too happy?” (2)siderable overlap among the various samples, no two of 7 . Positive affect Number of “Yes” responses to five questionsthem were identical; each sample consisted of those about positive feelings experienced in the past few weeks (2)patients for whom the necessary data were available. 8. Negative affect Number oT”No“ responses to five questions about negative feelings experienced inR e Lia bility the past few weeks (2) 9. Satisfaction “Which face (of seven, labeled from with life delighted to terrible) comes closest to Figure 1 shows a scatterplot of the nurse KPS rating expressing how you feel about your lifevs. the social worker ratings, with both ratings taken as a whole?” (1)in the clinic or hospital within one week of each other. 10. Overall “What is your estimate of your overallThe Pearson correlation between the two sets of ratings condition condition right now, on a scale of zero to loo?”was .69 ( P< .001), indicating a moderate degree of 3. TABLE Patient Characteristics Sex Age Primary cancer (%) Total Reliability sample no. Female Male Mean Range Lung Breast OtherNurse v . social worker 52 23 29 55 (22-82) 52 15 33Clinic vs. home 50 25 25 59 (28-85) 36 20 44Val idit y 52 30 22 59 (37-85) 31 27 42Deceased patients 104 42 62 57 (22-8 1) 48 6 46
  • 3. 2222 15 1980 CANCERA~~ Vol. 45 being taken within seven days of each other, is shown in Figure 2. Although the Pearson correlation coef- ‘80 ficient between the home and clinic scores (.66, P < .001) demonstrates a similar degree of interrater re- liability for the two clinic scores, there was a significant 4.. tendency for the clinic scores to be greater than the$a L. home scores; the average clinic score was over five points higher than the average home score (81 .O vs. n n e 75.3, P < .003 by a paired t-test). Validity Table 4 shows correlations (Pearson) between the KPS and other variables for which data were gathered at the same time. The KPS was strongly correlated with the variables most closely related to physical functioning (especially difficulty with balance and difficulty on stairs), and less strongly (but still sig- OV lb 2b A 40 &I $0 7b Bb 40 A nificantly) correlated with most of the variables related SOCIALWORKER KPS RATING to psychological status. The degree to which the KPSFIG. 1. Scatterplot of nurse vs. social worker KPS ratings (N = 52). may be useful as a predictor of survival can be seen in Figure 3, which shows a plot of on-study KPS scores vs. duration of survival for the 104 patients who haveinterrater reliability. There was no tendency for either died. A graph of the mean KPS scores for deceasednurses or social workers to rate patients higher; average patients taken at each of seven time points in the finalratings for the two sets were within a half point of phase of their disease is shown in Figure 4. Becauseeach other (70.2 for the nurses, 69.7 for the social it was felt that the graph in Figure 4 might appearworkers, with no significant difference as evaluated by different for patients with lung cancer as compared toa paired t-test). We were unable to discern any tendency other types of cancer, the mean KPS scores for patientsfor certain types of patients to show greater disparities with lung cancer over time were compared with thosebetween the nurse rating and the social worker rating. for patients with other cancers. At each of the seven A scatterplot of the clinic KPS ratings vs. the home time points there was no significant difference (by t-test).KPS ratings, again with the two ratings for each patient Discussion Many different measures are currently in use in clinical trials, including indices of disease status, checklists of symptoms, and signs and survival data. Because one of the major concerns of patients with advanced cancer is maintaining independence through self-care, it is desirable to be able to assess the patient’s degree of independent function. Earlier experience led to the KPS assessments done in the home and clinic at about the same time for comparison. Figure 2 indicates0 40- the KPS at home were often lower than those deter-z mined in the clinic. This probably reflects a tendency ford 30- patients’ problems to seem less severe outside their home and possibly a tendency for patients to put on a 20- “show” of well-being for clinic staff.“ - Correlations between the KPS and other variables 10 are shown in Table 4. The KPS showed a strong cor- relation with positive affect, but not negative, which suggests an explanation for the pattern of the cor- HOME KPS RATING relations. In a general sample of adults, Bradburn FIG.2 . Scatterplot of clinic vs. home KPS ratings (N = 50). found that negative affect was strongly associated with
  • 4. No. 8 EVALUATION PATIENTS OF USINGT H E KPS . Yatrs rt af. 2223the level of physical symptoms.2 However, when only TAB1.F 4. Correlations (Pearson) between KPS and Other Variables (45 5 N 5 49)those individuals suffering from a physical illness wereconsidered, the level of symptoms was not correlated Correlationwith negative affect. Similarly, having advanced cancer Variable with KPS*was a source of negative feelings for all of the pa- I . Desire for food .40 ( P < .002)tients in our sample, and it appears that variation in the 2. Sleep .24 ( P < ,050)degree to which their performance status was com- 3. Difficulty with balance .61 ( P < .001) 4. Difficulty with stairs .63 ( P < ,001)promised did not make much difference in how much 5 . Pain level -.37 ( P < ,006)negative feeling the patients reported. On the other 6. Happiness . I 2 (not significant)hand, Bradburn found that positive affect was related 7. Positive affect .54 ( P < ,001) 8. Negative affect -.09 (not significant)to participation in novel activities and becoming in- 9. Satisfaction with life .36 ( P < ,007)volved with one’s environment. For our sample, the 10. Overall condition .39 ( P < .004)degree to which patients were able to participate in All variables except pain level and negative affect are codedsuch activities was largely dependent on their physical + such that a higher score represents a higher level of functioning.status; hence the correlation between positive affectand the KPS. Thus it is possible that although theKPS is a useful overall indicator of physical status in score was not predictive of long-term survival becausea number of aspects, it may not reflect variation in many of the patients with high initial scores diedpsychological status beyond that associated with quickly. The KPS on Figure 4 reflects the progressivephysical dysfunction. The non-significant correlation deterioration of patients’ physical condition, with aof the KPS with happiness and the relatively weak considerable drop in the last two months of life.correlations of the KPS with overall condition and pain The KPS is designed to assess independent functionlevel (which certainly have both physical and psycho- and appears to have substantial validity as an indicatorlogical bases), support this view. of overall physical status. In particular, the association It is clear from Figure 3 that for this group of patients between low KPS scores and shortened life expectancya low KPS score was strongly associated with death suggests that the KPS may be valuable as a stratifica-within a relatively short time. Only one of the patients tion variable in randomizing patients for clinical trials.with an on-study KPS score of less than 50 survived In addition, improvement in KPS associated with re-longer than six months. On the other hand, a high KPS sponse t o treatment can be used as one objective 100 .. .. . “ . . . d . .. .. . . . . .. ..... ..... . . . . .. ..... + .a . a .. . -a FIG.3. Scatterplot of on-studyKPS scores vs. days before death a * 5 0 . .. .a ..ow( N = 104). ... ... lot d 1 1 I 6I 6 0I ~ !I 5 4 0 ~ 4 2 0 ~ 3 0 0 2 4 0 l m 1 m06 0 I 1 1 1 1 I DAYSBEFORE DEATH
  • 5. C A N C E R A ~ 1980 15 ~ Vol. 45 loo - measure of that response. It does not seem to reflect variations in psychological well-being measures, other 90- than those associated with physical disability. How- ever, its evident validity, reliability, and simplicity make it quite helpful as a criterion in clinical trials 80- for patients with cancer, and potentially for patients-Ljui+I 70- P I I with other chronic diseases with a fatal outcome. The evidence assembled in this study indicates that the performance status, long assumed to be a useful assessment of function, is in fact a fairly quantitative 60- measure with consistency among observers and a close8 50- correlation with deterioration in function as measured by other quantifiable parameters.ffx 40- REFERENCES 1. Andrews, F. M., and Withey, S. B.: Social Indicators of3z 30- Well-Being. New York, Plenum Press, 1976. 2 . Bradburn, N . M.: The Structure of Psychological Well- Being. Chicago, Aldine Publishing Company, 1969. 3 . Brown, T. M., Feins, A., Parke, R. C . , and Paulus, D. A,: 20- Living with long-term home dialysis. A n n . Int. Med. 81:165- 170, 1974. 1 0 - 4. Chalmer, B. J : Measuring “Quality of Life“ in Patients with Advanced Cancer. Master’s thesis, U. of Vermont, 1978. 5. Karnofskv, D. A., and Burchenal, J. If.: The clinical evaluation I I I I I 1 I I I of chemotherapeutic agents in cancer. In Evaluation of chemo-

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