Measuring the quality of life in hypertension according to Item Response Theory

Borges, José Wicto Pereira; Moreira, Thereza Maria Magalhães; Schmitt, Jeovani; Andrade, Dalton Francisco de; Barbetta, Pedro Alberto; Souza, Ana Célia Caetano de; Lima, Daniele Braz da Silva; Carvalho, Irialda Saboia

doi:10.1590/S1518-8787.2017051006845

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Original Articles • Rev. Saúde Pública 51 • 2017 • https://doi.org/10.1590/S1518-8787.2017051006845 copy

Measuring the quality of life in hypertension according to Item Response Theory

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

OBJECTIVE

To analyze the Miniquestionário de Qualidade de Vida em Hipertensão Arterial (MINICHAL – Mini-questionnaire of Quality of Life in Hypertension) using the Item Response Theory.

METHODS

This is an analytical study conducted with 712 persons with hypertension treated in thirteen primary health care units of Fortaleza, State of Ceará, Brazil, in 2015. The steps of the analysis by the Item Response Theory were: evaluation of dimensionality, estimation of parameters of items, and construction of scale. The study of dimensionality was carried out on the polychoric correlation matrix and confirmatory factor analysis. To estimate the item parameters, we used the Gradual Response Model of Samejima. The analyses were conducted using the free software R with the aid of psych and mirt.

RESULTS

The analysis has allowed the visualization of item parameters and their individual contributions in the measurement of the latent trait, generating more information and allowing the construction of a scale with an interpretative model that demonstrates the evolution of the worsening of the quality of life in five levels. Regarding the item parameters, the items related to the somatic state have had a good performance, as they have presented better power to discriminate individuals with worse quality of life. The items related to mental state have been those which contributed with less psychometric data in the MINICHAL.

CONCLUSIONS

We conclude that the instrument is suitable for the identification of the worsening of the quality of life in hypertension. The analysis of the MINICHAL using the Item Response Theory has allowed us to identify new sides of this instrument that have not yet been addressed in previous studies.

Quality of Life; Hypertension; Sickness Impact Profile; Surveys and Questionnaires, utilization; Validation Studies

Items	Models
	One-dimensional	Two-dimensional*
	F1	F1	F2
1. Have you not been sleeping well?	0.47	0.40	0.12
2. Has it been difficult to keep your usual social relationships?	0.55	0.23	0.48
3. Has it been difficult to relate to people?	0.45	0.14	0.47
4. Do you feel that you are not exercising a useful role in life?	0.41	-0.05	0.66
5. Do you feel unable to make decisions and initiate new things?	0.46	-0.06	0.76
6. Have you been feeling constantly agonized and tense?	0.70	0.53	0.27
7. Do you feel that life is a continuous struggle?	0.38	0.20	0.27
8. Do you feel unable to enjoy your usual daily activities?	0.50	0.07	0.63
9. Have you been feeling exhausted and without strength?	0.75	0.61	0.24
10. Have you felt that you were sick?	0.62	0.55	0.13
11. Have you noticed difficulty breathing or shortness of breath without apparent cause?	0.67	0.77	-0.08
12. Have you had swollen ankles?	0.37	0.44	-0.07
13. Have you noticed that you urinate more frequently?	0.25	0.20	0.08
14. Have you been feeling your mouth dry?	0.56	0.50	0.12
15. Have you been feeling chest pain without making a physical effort?	0.67	0.79	-0.10
16. Have you noticed numbness or tingling in any part of your body?	0.53	0.63	-0.09
17. Would you say your hypertension and its treatment have affected your quality of life?	0.42	0.33	0.15
Explained variance (%)	28.20	28.20	9.33

CFA adjustment indexes for each model
GFI	0.973	0.985
AGFI	0.956	0.976
NFI	0.926	0.959
TLI	0.934	0.972
CFI	0.943	0.976
RMSEA	0.067	0.043

Items^a		Parameters
Items^a		a (SE)	b2 (SE)	b3 (SE)	b4 (SE)
Mental state
1	Have you not been sleeping well?	0.90 (0.11)	-0.17 (0.09)	0.67 (0.10)	1.95 (0.12)
2	Has it been difficult to keep your usual social relationships?	1.12^b (0.15)	1.30 (0.13)	2.06 (0.17)	2.76 (0.21)
3	Has it been difficult to relate to people?	0.87 (0.15)	2.03 (0.14)	2.95 (0.19)	3.93 (0.26)
4	Do you feel that you are not exercising a useful role in life?	0.76 (0.12)	1.33 (0.11)	2.23 (0.13)	3.17 (0.15)
5	Do you feel unable to make decisions and initiate new things?	0.88 (0.12)	1.23 (0.11)	2.09 (0.13)	3.17 (0.18)
6	Have you been feeling constantly agonized and tense?	1.66^b (0.14)	-0.37 (0.12)	0.52 (0.12)	1.25 (0.15)
7	Do you feel that life is a continuous struggle?	0.70 (0.09)	-2.19 (0.11)	-0.82 (0.09)	0.73 (0.09)
8	Do you feel unable to enjoy your daily activities?	0.97 (0.12)	0.77 (0.10)	1.69 (0.12)	2.79 (0.16)
9	Have you been feeling exhausted and without strength?	1.95^b (0.17)	-0.29 (0.13)	0.54 (0.14)	1.28 (0.19)
Somatic manifestations
10	Have you felt that you were sick?	1.34^b (0.12)	-0.25 (0.11)	0.81 (0.12)	1.67 (0.15)
11	Have you noticed difficulty breathing or shortness of breath without apparent cause?	1.53^b (0.16)	0.57 (0.12)	1.46 (0.17)	2.20 (0.23)
12	Have you had swollen ankles?	0.68 (0.10)	0.90 (0.09)	2.26 (0.11)	3.25 (0.14)
14	Have you been feeling your mouth dry?	1.15^b (0.12)	0.15 (0.10)	1.09 (0.12)	1.75 (0.13)
15	Have you been feeling chest pain without making a physical effort?	1.52^b (0.16)	0.64 (0.12)	1.68 (0.19)	2.57 (0.30)
16	Have you noticed numbness or tingling in any part of your body?	1.06^b (0.11)	-0.38 (0.10)	1.14 (0.11)	1.99 (0.14)
17	Would you say your hypertension and its treatment have affected your quality of life?	0.78 (0.10)	0.83 (0.10)	1.75 (0.11)	2.85 (0.14)

Anchoring of items	Level	Description	% of patients
Category “No, absolutely”	Below 35 (Very high quality of life in hypertension)	Patients at this level of the scale have very high quality of life in hypertension.	5.80
I7b2	35 to 50 (High quality of life in hypertension)	In general, patients located at this level still have a high quality of life in hypertension; however, they have a slight sensation that life is a continuous struggle.	45.80
I1b2, I6b2, I9b2, I10b2, I11b2, I14b2, I15b2, I16b2, I6b3, I7b3, I9b3	50 to 65 (Moderate quality of life in hypertension)	Patients at this level have moderate quality of life, have an enough sensation that life is a continuous struggle and, in general, feel a little sick. Although in a lighter degree, they complain of not sleeping well, feeling tense, agonized, exhausted, and without strength. Other somatic manifestations, such as difficulty breathing, dry mouth, numbness and tingling of some part of the body, and chest pain without making an effort, are more likely to be present in patients located at this level of quality of life in hypertension.	40.00
I2b2, I3b2, I4b2, I5b2, I8b2, I12b2, I1b3, I2b3, I5b3, I8b3, I10b3, I11b3, I14b3, I15b3, I16b3, I17b3, I1b4, I6b4, I7b4, I9b4, I10b4, I11b4, I14b4, I16b4	65 to 80 (Low quality of life in hypertension)	At this level, there is a low quality of life. The hypertension and the treatment considerably affect the quality of life. There is a worsening of the sleep quality and issues related to mental health, such as: difficulty in relating to people, feeling worthlessness, inability to make decisions and initiate new things, and enjoying usual daily activities. There is a worsening of the somatic symptoms described at the previous level (chest pain, tingling, exhaustion) in addition to the appearance of swelling in the ankles.	8.10
I2b3, I4b3, I12b3, I2b4, I4b4, I5b4, I8b4, I12b4, I15b4, I17b4	Above 80 (Very low quality of life in hypertension)	Patients at this level of the scale have very low quality of life. The hypertension and the treatment considerably affect the quality of life, and there is a worsening of all mental and somatic manifestations observed in the instrument.	0.30

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[1] Correspondence: José Wicto Pereira Borges. Universidade Federal do Piauí. BR 343 km 3,5 Meladão 64800-000 Floriano, PI, Brasil. E-mail: wictoborges@yahoo.com.br