Association of Grit Scores With Treatment Adherence and Biomarkers in Patients With Type 2 Diabetes

One in 12 adults worldwide has diabetes.¹ Medical treatment can reduce diabetes-related complications, but adherence to treatment can be difficult.² The reasons for nonadherence are multifactorial. Social scientists have found that character skills—sometimes referred to as socioemotional, noncognitive, or soft skills—are an important factor in whether people succeed in long-term challenges. For instance, the concept of grit, which is defined as “perseverance and passion for long-term goals,”³ is associated with success in challenging domains and is independent of intelligence. This cohort study explores whether scores on the grit scale are associated with treatment adherence and biomarker levels in patients with type 2 diabetes.

The ethics committee of the National Institute of Medical Science and Nutrition Salvador Zubirán approved the study. The study participants provided written informed consent. The reporting of this study conforms to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.⁴

Between October 2017 and November 2018, surveys were conducted among patients with type 2 diabetes at the hospital of the National Institute of Medical Science and Nutrition Salvador Zubirán immediately before their scheduled medical consultation. The survey included 4 questions on self-reported adherence to treatment, diet, and exercise, as well as the Short Grit Scale (Grit-S), which is computed as the mean of 8 items in which patients rate their perseverance of effort and consistency of interest on a 5-point Likert scale.⁵ Unlike patient-engagement metrics, the Grit-S does not include questions about a patient’s knowledge of the disease or treatments and, therefore, is a priori independent of medical outcomes. Patient socioeconomic information and laboratory data from a few days before the scheduled medical consultation and survey date were obtained from hospital records.

Multivariable linear regression analysis of adherence, biomarkers, and Grit-S scores was performed both with and without adjustment for covariates, which included 7 categories of socioeconomic status (determined and coded by hospital social workers on the basis of patient information, such as household income, dwelling characteristics, and occupation of the primary income earner) and cubic polynomials for years of schooling and number of years with diabetes. Analysis was performed using Stata statistical software version 15.0 (StataCorp), and the 95% confidence interval around estimates reflects 0.025 in each tail; 2-tailed P ≤ .05 (t test) was considered statistically significant.

A total of 442 patients (275 [62%] female; mean [SD] age, 64 [12] years; age range, 24-93 years) were surveyed in person. The response rate was 100%. The patients had a mean (SD) of 10 (5) years of schooling (range, 0-26 years) and a mean (SD) of 17 (10) years with type 2 diabetes (range, 0-47 years). The percentage of patients who adhered to treatment ranged between 48.5% and 72.3%, depending on the measure of adherence (Table 1). Grit was associated with greater adherence in all measures. An increase of 1 SD in the Grit-S score was associated with an increase in adherence of 6.1% to 12.3%, depending on the measure analyzed (Table 1). Results were similar with multivariable adjustment.

Mean (SD) laboratory values were as follows: triglycerides, 174.9 (132.8) mg/dL (to convert to millimoles per liter, multiply by 0.0113); total cholesterol, 175.0 (47.8) mg/dL (to convert to millimoles per liter, multiply by 0.0259); glycated hemoglobin, 8.17% (1.99%) (to convert to proportion of total hemoglobin, multiply by 0.01); and serum glucose, 145.1 (60.1) mg/dL (to convert to millimoles per liter, multiply by 0.0555) (Table 2). Grit was associated with lower levels of each measure. An increase of 1 SD in the Grit-S score was associated with lower triglyceride (change, −17.8 mg/dL; 95% CI, −30.5 to −5.1 mg/dL), cholesterol (change, −6.3 mg/dL; 95% CI, −10.9 to −1.7 mg/dL), glycated hemoglobin (change, −0.17%, 95% CI, −0.36% to 0.02%), and glucose (change, −5.1 mg/dL, 95% CI, −10.8 to 0.7 mg/dL) levels. Results were similar with multivariable adjustment.

To our knowledge, this study is the first to analyze the association between patient Grit-S score, treatment adherence, and measures of disease control. Among patients with type 2 diabetes, grit was associated with greater treatment adherence and better glycemic and cholesterol control. Because character skill scales used by social scientists can be routinely measured among patients as they start treatment, these findings suggest that programs aimed at increasing treatment adherence may optimally focus on patients who, on the basis of the scores in those scales, are likely to display low adherence. These findings also suggest the importance of soft skills in overcoming long-term health challenges, such as managing diabetes. Study limitations include the analysis of observational data, which precludes a causal interpretation of the association between grit and treatment adherence, a focus on patients with type 2 diabetes, and analyses performed in a single center.

Accepted for Publication: July 29, 2019.

Published: September 13, 2019. doi:10.1001/jamanetworkopen.2019.11476

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Peña PA et al. JAMA Network Open.

Corresponding Author: Anupam B. Jena, MD, PhD, Department of Health Care Policy, Harvard Medical School, 180 Longwood Ave, Boston, MA 02115 (jena@hcp.med.harvard.edu).

Author Contributions: Dr Peña had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Peña, Pérez-Díaz, Pulido-Ayala, López-Navarro, Duckworth.

Acquisition, analysis, or interpretation of data: Peña, Pulido-Ayala, Osorio-Landa, López-Navarro, Jena.

Drafting of the manuscript: Peña, Pérez-Díaz, Pulido-Ayala, Osorio-Landa, López-Navarro.

Critical revision of the manuscript for important intellectual content: Peña, Pulido-Ayala, Duckworth, Jena.

Statistical analysis: Peña, Pulido-Ayala, López-Navarro.

Administrative, technical, or material support: Pérez-Díaz, Pulido-Ayala, Osorio-Landa, López-Navarro.

Supervision: Pérez-Díaz, Pulido-Ayala, Osorio-Landa, López-Navarro, Jena.

Conflict of Interest Disclosures: Dr Jena reported receiving consulting and personal fees unrelated to this work from Pfizer, Hill-Rom Services, Bristol-Myers Squibb, Novartis, Amgen, Eli Lilly, Vertex Pharmaceuticals, AstraZeneca, Celgene, Tesaro, Sanofi-Aventis, Biogen, Precision Health Economics, and Analysis Group. No other disclosures were reported.

Funding/Support: This work was supported by grant 1DP5OD017897 from the National Institutes of Health to Dr Jena.

Role of the Funder/Sponsor: The National Institutes of Health had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.