Association Between Insufficient Sleep, Health-Related Quality of Life, and Life

Satisfaction, Among Adults with Asthma: A Mediation Model Approach.

Lauren N. Drinkard, BGS , AACandidate for MPH in Biostatistics, College of

Public Health, Kent, Ohio

Introduction: Prevalence of Asthma

Shiller, JS, et al. (2010); http://www.cdc.gov/asthma/

Asthma is a chronic respiratory disease

Prevalent in 8% of the U.S. adult population

1 in 12

Introduction: Public Health Burden of Asthma

http://aafa.org; National Heart Lung and Blood Institute, 2009; Ampon, 2005

Burdens on individuals, workplace, and society

High healthcare costs (20B)Lost work productivity

Healthy People 2020

How does asthma impact individuals?

Introduction: General Public and Life Satisfaction

U.S. Department of Health and Human Services.; Ampon, R., et al. 2005, Wilson, 1995, Gorman, 2009

Life satisfaction (LS)Insufficient Sleep (IS)Health related quality of life

(HRQOL)

IS LS

HRQOL

Study Rationale

Gorman, 2009; Carlton, 2005; Guney, 2010; Fagerstrom, 2011; Zullig, 2004; Strine, 2008

Asthmatic adults = sleep abnormalities

Insufficient sleep HRQOL

Insufficient sleep reduced life satisfaction

HRQOL reduced life satisfaction

Purpose & Objective

Zullig, 2004; Strine, 2008; Colas, 2011; Trojan, 2012

The purpose of this research was to examine the effect of insufficient sleep on life satisfaction in adults with asthma and to determine if HRQOL indicators mediate the effect.

BRFSS 2010 Total Subjects N = 451,075

Have you ever been told you had asthma? If yes, do you still have asthma?

n = 41,518

Are you pregnant?n = 270

Missing data on predictor, mediators, or outcome

n = 4,586

*n = 36,662 *Subjects in the final sample size could be missing observations on one or more of the covariates

Figure I. Diagram of Sample Size

Methods: Definitions

Outcome: Life SatisfactionSatisfied (very satisfied/satisfied) Dissatisfied (very dissatisfied/dissatisfied)

Exposure: Insufficient Sleep0-13 days and 14-30 days

Mediators: HRQOLPhysical Health, Mental Health, Overall Physical Health

• 0-13 days and 14-30 daysGeneral Health

• Good (excellent/very good/good)• Not Good (fair/poor)

Methods: Covariates

Healthcare insurance status

Ability limitation due to health problems

Health problems requiring special equipment

Number of comorbid conditions

Demographics

Socioeconomic Status

Statistical Analysis

Weighted prevalence estimates: Insufficient sleepHRQOLLife satisfactionCovariates

Logistic regression models were used to study the effect of insufficient sleep on life satisfaction that is mediated through HRQOL indicators

SAS V9.2

MacKinnon, 1993; Barron and Kenny, 1986; Preacher, 2004

Results: Table I Characteristics

n n n

Age, m (SD)

18-99 years old 36446 46.23 (45.85 - 46.61) 32791 46.28 (45.88 - 46.68) 3655 45.74 (44.65 - 46.84)

Gender, n (%)

Male 9882 36.72 (35.63 - 37.10) 8941 36.64 (35.50 - 37.79) 941 37.39 (33.91 - 40.88)

Female 26780 63.28 (62.20 - 64.37) 24047 63.36 (62.21 - 64.50) 2733 62.61 (59.12 - 66.09)

Race, n (%)

White (Non-Hispanic) 28265 69.37 (68.32 - 70.41) 25538 69.61 (68.51 - 70.71) 2727 67.17 (63.90 - 70.43)

Black (Non-Hispanic) 3362 11.45 (10.73 - 12.16) 2995 11.41 (10.65 - 12.17) 367 11.78 (9.82 - 13.75)

Other (Non-Hispanic) 1365 4.21 (3.73 - 4.68) 1214 4.16 (3.65 - 4.66) 151 4.66 (3.15 - 6.16)

Multi-Racia l (Non-Hispanic) 1034 2.82 (2.49 - 3.15) 895 2.66 (2.33 - 2.99) 139 4.29 (2.90 - 5.68)

Hispanic 2233 11.26 (10.45 - 12.07) 1988 11.26 (10.41 - 12.11) 245 11.25 (8.60 - 13.89)Number of Chronic Conditi ons (CVD, CHD, Stroke, Diabetes ), n (%)

0 26108 78.97 (78.22 - 79.71) 23924 80.21 (79.45 - 80.98) 2184 67.57 (64.72 - 70.41)

1 6855 14.23 (13.59 - 14.87) 5962 13.69 (13.02 - 14.36) 893 19.18 (17.01 - 21.36)

2+ 3699 3.80 (6.39 - 7.21) 3102 6.10 (5.70 - 6.49) 597 13.25 (11.21 - 15.29)

Table I . Socioeconomic Characteristics of Asthmatic Study Participants by Li fe Satisfaction (n = 36,662)

Overall Very Satisfied/Satisfied Dissatisfied/Very DissatisfiedUnadjusted Weighted

Proportion, % Estimate (95% CI)

Unadjusted Weighted Proportion, % Estimate

(95% CI)

Unadjusted Weighted Proportion, % Estimate

(95% CI)

X (Insufficient Sleep) Y (Life Satisfaction)

Mediators (HRQOL)Mental Health

a b

direct effect: c’

indirect effect: a*b

Mediation Model Approach

total effect: c

X (Insufficient Sleep) Y (Life Satisfaction)

𝑌=𝛽0+𝑐′ 𝑋+𝑏𝑀+𝑍+𝑒

Standardized Total Effect

= c total effect

Std(c) =

total effect = c = 0.2433

X (Insufficient Sleep) Y (Life Satisfaction)

c ∗ sd(𝑋)ඥσ2(Y′)

where, σ2(Y’) = c2σ2X + 3.4971 = [(0.944*0.944)0.2324]+

0.2433 =

c

Standardized Direct effect

= 0.6340

Std(c’) =

where, σ2(Y*) = c’2σ2X + b2σ2M + 2cov(X,M) +

X (Insufficient Sleep) Y (Life Satisfaction)

Mediators (HRQOL)Mental Health

c’

c′ ∗ sd(𝑋)ඥσ2(Y∗) 0.1551 =

3.8795 = [(0.6340*0.6340)0.2324]+[(1.5440*1.5440)]+2(0.1582) +

direct effect = c’ = 0.1551

Standardized Indirect effect

Std(b) =

where, σ2(Y*) = c’2σ2X + b2σ2M + 2cov(X,M) + σ2(Y*) = 3.8795

Std(a)=

where σ2(M’) = α2σ2X +

X (Insufficient Sleep) Y (Life Satisfaction)

Mediators (HRQOL)Mental Health

a b

0.2882 =

b ∗ sd(𝑀)ඥσ2(Y∗)

α ∗ sd(𝑋)ඥσ2(M′)

3.5882 = [(1.1327*1.1327)0.2324]+

0.3119 =

= 1.5440 a = 1.1327

indirect effect: a*b = 0.0899

Estimate the Proportion Mediated

Proportion of total effect mediated by HRQOL Mental HealthIndirect effect/Total effect

Std a*Std b /Std c

36.95% = 0.0899/0.2433

37% of the effect of insufficient sleep on life satisfaction was mediated by the HRQOL indicator mental health.

Results of Proportion Mediated

X (Insufficient Sleep) Y (Life Satisfaction)

Mediators (HRQOL)Mental Health: 36.9%

Overall Poor Health: 22.2% General Health: 16.1% Physical Health: 11.7%

Limitations and Strengths

LimitationsNot able to account for

the severity of asthma

No temporality, so unable to show causation

StrengthsTo our knowledge, first

study to measure the magnitude of the mediated effect of HRQOL among asthmatic adults

Discussion

Gorman, 2009; ; Guney, 2010; Trojan, 2012; Fagerstrom, 2011 CDCd; Carlton, 2005’ Zullig, 2004; Strine, 2008

Internal consistency of results

External consistency support by previous research

Practicality of findings and impact for asthmatics

Unanswered questions

HRQOL mediates the association between IS LS

Conclusion

Cross-sectional study suggests strong association between insufficient sleep, HRQOL, and overall life satisfaction

Provides new evidence that HRQOL mediates the relationship between IS LS

Public health practitioners should be aware of sleep quantity and quality as they have implications for health outcomes in adults with asthma.

Acknowledgments

Dr. Cheruvu

Kent State University College of Public Health

2010 BRFSS study participants

QUESTIONS?

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