The Relationship between Patient Satisfaction with Service Quality ...

RESEARCH ARTICLE

The Relationship between Patient Satisfaction with Service Quality and Survival in Non-Small Cell Lung Cancer – Is Self-Rated Health a Potential Confounder? Christopher G. Lis, Kamal Patel, Digant Gupta* Cancer Treatment Centers of America (CTCA), 500 Remington Road, Schaumburg, Illinois, 60173, United States of America * [email protected]

Abstract Background/Aims Citation: Lis CG, Patel K, Gupta D (2015) The Relationship between Patient Satisfaction with Service Quality and Survival in Non-Small Cell Lung Cancer – Is Self-Rated Health a Potential Confounder? PLoS ONE 10(7): e0134617. doi:10.1371/journal.pone.0134617

Previously we reported that higher patient satisfaction (PS) with service quality is associated with favorable survival outcomes in a variety of cancers. However, we cautioned the readers that patients with greater satisfaction might be the ones with better self-rated health (SRH), a well-established prognosticator of cancer survival. In other words, SRH could potentially confound the PS and survival relationship. We investigated this hypothesis in non-small cell lung cancer (NSCLC).

Editor: Ramon Andrade de Mello, University of Algarve, PORTUGAL

Methods

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Received: May 11, 2015 Accepted: July 11, 2015 Published: July 31, 2015 Copyright: © 2015 Lis et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Data cannot be made publicly available due to ethical and legal restrictions. However, a copy of the de-identified dataset underlying the analyses reported in this paper is available upon request to the corresponding author. Funding: The authors have no support or funding to report. Competing Interests: The authors have declared that no competing interests exist.

778 NSCLC patients (327 males and 451 females; mean age 58.8 years) treated at 4 Cancer Treatment Centers of America hospitals between July 2011 and March 2013. PS was measured on a 7-point scale ranging from “completely dissatisfied” to “completely satisfied”. SRH was measured on a 7-point scale ranging from “very poor” to “excellent”. Both were dichotomized into 2 categories: top box response (7) versus all others (1–6). Patient survival was the primary end point. Cox regression was used to evaluate the association between PS and survival controlling for covariates.

Results 74, 70, 232 and 391 patients had stage I, II, III and IV disease respectively. 631 (81.1%) patients were “completely satisfied”. 184 (23.7%) patients had “excellent” SRH. There was a weak but significant correlation between overall PS and SRH (Kendall’s tau b = 0.19; p 0.70) of Kendall’s tau b correlation coefficient were used as an initial screen for pairs of PS measures. Kendall’s tau b is an appropriate measure of association for categorical variables and is commonly used when both variables have the same number of categories. As a second check, the variance inflation factor (VIF) was used with the final model to verify that multicollinearity was not significantly influencing model coefficients [34;35]. All data were analyzed using IBM SPSS version 20.0 (IBM, Armonk, NY, USA). A difference was considered to be statistically significant if the p value was less than or equal to 0.05.

Results Response Rate A total of 1,111 returning NSCLC patients were contacted at all four hospitals combined to participate in the survey between July 2011 and March 2013. However, only 778 patients responded. As a result, the response rate for this study was 70%.

Baseline Patient Characteristics Table 1 displays baseline patient characteristics of the entire study population (N = 778). At the time of this analysis (June 2014), 317 (40.7%) patients had expired. A majority of the patients were newly diagnosed at our institution and had advanced stage (III or IV) disease at diagnosis. The median time duration between the date first seen at CTCA and the date of PS survey was 5 months. Table 2 describes the distribution of PS items. 631 (81.1%) patients were “completely satisfied” with the overall service quality they received. The highest levels of dissatisfaction were observed for the following 3 individual PS items in terms of percent “not completely satisfied”: waiting time for appointments (32.7%), the response/call back from scheduling after you have left a message (23.5%) and care manager’s effectiveness in helping with your care when you are at home (20.7%). 184 (23.7%) patients had “excellent” SRH.

PLOS ONE | DOI:10.1371/journal.pone.0134617 July 31, 2015

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Patient Satisfaction, Self-Rated Health and Survival

Table 1. Baseline Patient Characteristics. Variable

Categories

Number (Percent)

Age at the time of first survey

Mean

58.8

Median

58.9

Gender CTCA Hospital

Stage at diagnosis

Treatment History

Range

31–94

Males

327 (42)

Females

451 (58)

Midwestern

311 (40)

Southwestern

191 (24.5)

Eastern

210 (27)

Western

66 (8.5)

Stage I

74 (9.5)

Stage II

70 (9)

Stage III

232 (29.8)

Stage IV

391 (50.3)

Indeterminate

11 (1.4)

Newly Diagnosed

521 (67)

Previously Treated

257 (33)

(CTCA = Cancer Treatment Centers of America) doi:10.1371/journal.pone.0134617.t001

Correlation Analysis Table 3 displays Kendall’s tau b correlation coefficients among the PS items and SRH. The correlations among the PS items were weak to strong (ranging from 0.23 to 0.74) and all were statistically significant at the 0.01 level. The correlations between SRH and PS items were weak (ranging from 0.13 to 0.19) but statistically significant at the 0.01 level.

Univariate Analysis—Predictors of Patient Survival On Kaplan-Meier analysis, median overall survival for the entire patient cohort was 14.4 months (95% CI: 12.7–16.1 months). The median survival for “completely satisfied” patients Table 2. Distribution of Patient Satisfaction Items. How satisfied are you in the following areas:

Completely Satisfied

Team giving you the information you need to understand your medical condition (n = 764)

635 (83.1)

Team explaining your treatment options (n = 759)

629 (82.9)

Team involving you in decision making as much as you preferred (n = 755)

648 (85.8)

Teams communicating with each other concerning your medical condition and treatment (n = 759)

615 (81)

Care manager’s effectiveness in helping with your care when you are at home (n = 704)

558 (79.3)

Team treating you with respect and in a professional manner (n = 760)

716 (94.2)

The response/call back from scheduling after you have left a message (n = 732)

560 (76.5)

Waiting time for appointments (n = 753)

507 (67.3)

Treating medical oncologist (n = 755)

680 (90.1)

• Items were dichotomized into two groups of “completely satisfied (7)” and “not completely satisfied (1–6)” • Some sample sizes are less than 778 because of missing responses doi:10.1371/journal.pone.0134617.t002


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.43

Respectful Treatment

.17

.29

.28

.44

.46

.46

.45

.45

.48

1.0

Medical Oncologist

.18

.36

.36

.47

.54

.69

.57

.74

1.0

Information

doi:10.1371/journal.pone.0134617.t003

• ll c All correlations were significant at the 0.01 level

.19

.48

Help with Home Care

Overall Health

.50

Team Communication

.39

.47

Involvement in Decisions

.36

.52

Explaining Treatment

Waiting Time

.55

Information

Scheduling

.55

1.0

Overall Satisfaction

Medical Oncologist

Overall Satisfaction

Kendall’s tau b

.16

.37

.33

.42

.53

.70

.69

1.0

Explaining Treatment

.15

.34

.34

.43

.56

.67

1.0

Involvement in Decisions

Table 3. Correlation Analysis of Patient Satisfaction Items with Self-Rated Health.

.17

.42

.38

.49

.58

1.0

Team Communication

.15

.38

.40

.41

1.0

Help with Home Care

.13

.23

.28

1.0

Respectful Treatment

.14

.54

1.0

Scheduling

.16

1.0

Waiting Time

1.0

Overall Health


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and “not completely satisfied” patients was 14.9 and 11.9 months respectively, log-rank p = 0.04. The median survival for patients with “excellent SRH” and those with “not excellent SRH” was 19.7 and 12.5 months respectively, log-rank p = 0.001. As shown in Table 4, the individual PS items that were significantly predictive of survival on univariate Cox regression analysis were: “team giving you the information you need to understand your medical condition”, “team explaining your treatment options”, “team involving you in decision making as much as Table 4. Univariate Cox Regression Analysis. Variable

HR

95% CI

P-value

Team giving you the information you need to understand your medical condition

0.69

0.52 to 0.91

0.009*

Team explaining your treatment options

0.56

0.42 to 0.73