Journal Article
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Diminished Physical Function in Older HIV+ Adults Despite Successful Antiretroviral Therapy

Reported by Jules Levin
20th International AIDS Conference, July 20-25, 2014, Melbourne

Audrey Lan, Miriam Morey, PhD, Tammy Chin, Lynn McNeil, RN, Barlett Humphries, Katherine Frankey, Carl Pieper, DPH, Charles Hicks, MD, Mehri McKellar, MD Duke University, Durham, North Carolina

“More than 50% of HIV-infected adults in the US will be >50 years old in 2015……There is growing concern among patients and healthcare providers that this group is experiencing a premature or ‘accelerated aging’ process……We determined that HIV-infected older adults on effective ART (with suppressed HIV-1 viral loads) had diminished physical performance results when compared to normal reference controls…..Physical function was significantly diminished in older HIV+ persons when compared to reference standards for HIV- age/gender-matched controls. The magnitude of differences observed may be associated with poorer health, more disabilities, longer hospital stays, and higher costs, thus warranting intervention.”

Conclusions

  • The number of older adults who are HIV-infected is increasing in clinics nationwide, including in the Duke HIV clinic where 45% of the patients are 50 years old or older.
     
  • It is important to identify whether these older adults have diminished physical performance in order to prevent future complications, such as falls or disability.
     
  • We determined that HIV-infected older adults on effective ART (with suppressed HIV-1 viral loads) had diminished physical performance results when compared to normal reference controls.Physical performance did not significantly differ between those with CD4 nadir <200 versus >350 cells/mm3.
    • We observed clinically significant meaningful differences for the 8-foot walk and the 6-minute walk tests.
       
    • For the 8-foot walk test, the usual gait speed of participants was slower than the walking speed needed to safely cross the street.
       
    • For the 30-second chair stand and 6-minute walk test, participants did not meet the criteria predicted necessary to remain physically independent through life expectancy.

References: Bohannon(Age and Aging, 1997) for gait speed, Milanovic et at. (Clinical Interventions in Aging, 2013) for 30-second chair stands, Luna-Heredia et al. (Clinical Nutrition, 2005) for grip strength, Enright et al. (American Journal of Respiratory and Critical Care Medince, 1998) for 6 minute walk test.

Introduction/Background

  • More than 50% of HIV-infected adults in the US will be ≥50 years old in 2015.
     
  • There is growing concern among patients and healthcare providers that this group is experiencing a premature or ‘accelerated aging’ process.
     
  • It is not clear whether this is due to increased risk of age-associated conditions, lifestyle, co-morbidities, chronic HIV infection and/or prolonged antiretroviral therapy (ART).
     
  • Prior studies on functional status have shown that there is a greater decline in physical performance among HIV-infected persons compared to HIV-negative matched controls.
     
  • Most studies on physical performance in HIV patients have included younger, white male patients, and the majority of performance measures have been evaluated via self-reported questionnaires rather than directly measured.

Objectives

  • To develop a cohort of HIV-infected adults age 50 and older in line Duke HIV Clinic.
     
  • To assess functional status in older HIV-infected adults on effective antiretroviral therapy via 4 validated physical performance tests and to compare results to reference ranges for normal controls of similar age and gender.
     
  • To identify and characterize the impact of HIV-induced immunosuppression (as measured by the Nadir CD4 count) on physical function in older HIV-infected adults.

Participants: 108 patients in the Duke HIV Clinic ≥50 years old.

Inclusion criteria: Age 50 or older, currently stable on ART for at least 6 months, with undetectable HIV-1 viral loads and no HIV-1 are in a >200 copies/mL in the prior 12 months.

Exclusion criteria: Active unstable angina, recent (<6 months) hx of myocardial infarction, hx of ventricular tachycardia, uncontrolled hypertension (diastolic BP >120 mm/Hg), recent (<6 months) hx of stroke or any residual neurological deficits affecting physical function, active substance abuse affecting participation in study, dementia or diagnosis of mental or behavioral disorders that preclude study participation, severe hearing or vision loss, and/or chronic pain that may limit performance testing.

Design: All patients completed a one-time visit to obtain demographics, vital signs, body mass index (BMI), estimated duration of HIV, types and dates of current/prior ART, HIV-associated complications and opportunistic infections, additional medical conditions, lifestyle habits, nadir and current CD4 counts, and initial/baseline HIV-1 viral loads. Statistics were calculated with the MEANS procedure and the Wilcoxon two-sample test.³

Physical Performance Tests:

  • 8-Foot Walk (gait speed): Subjects walking measured course at usual and maximal walking speed. Good indicator of functional status; predictive of future institutionalization in survival/mortality.
     
  • 30-Second Chair Stand (lower extremity strength): Subjects stand all the way up and down from a chair as many times as possible in 30 seconds. Good indicator of mobility; can discriminate between fallers and non-fallers.
     
  • Grip strength (muscle function/strength): Subjects squeeze a dynamometer to measure grip strength. Predictive of mortality.
     
  • 6-Minute Walk Test (aerobic endurance): Subjects walk as fast as possible down a hallway and around a cone and back for 6 minutes. Measures exercise capacity; good indicator of global functional capacity and aerobic endurance.

Results

Overall demographics and clinical characteristics

  • 108 older HIV-infected patients on ART with HIV-1 <200 copies/mL enrolled
     
  • Mean age was 60.3 years (range 50.2–78.1)
     
  • Mean BMI was 28.6 kg/m² (range 17.4–51.2)
     
  • Mean length of time since HIV diagnosis was 15.3 years (range 1.4–31.7)
     
  • Mean current CD4 count was 691 cells/mm³ (range 83–2096)
  Total
(n=108)
CD4 nadir <200
cells/mm³ (n=73)
CD4 nadir ≥350
cells/mm³
Age      
50–59 years old 53 (49%) 37 (51%) 16 (46%)
60–69 years old 49 (45%) 31 (42%) 18 (51%)
≥70 years old 6 (6%) 5 (7%) 1 (3%)
Gender      
Male 76 (70%) 50 (60%) 26 (74%)
Female 32 ( 30%) 23 (32%) 9 (26%)
Race/Ethnicity      
Black/African-American 64 (59%) 48 (66%) 16 (46%)
White/Caucasian 41 (38%) 23 (31%) 18 (51%)
Hispanic 3 (3%) 2 (3%) 1 (3%)
BMI      
<25 kg/m² 28 (26%) 21 (29%) 7 (20%)
25–29.9 kg/m² 43 (40%) 30 (41%) 13 (37%)
>30 kg/m² 37 (34%) 22 (30%) 15 (43%)

Physical Performance Results Compared to Age/Gender-Matched Reference Ranges

  • Results from all 4 physical performance test showed diminished performance when compared to normal reference range for healthy, older adults by age and gender.
  n Did Difference From Norms Clinically Significant Meaningful Difference
Gait Speed – Usual Speed (m/s) 108 -0.20 ± 0.25 >0.1 m/s
Gait Speed – Maximal Speed (m/s) 108 -0.21 ± 0.37 >0.1 m/s
30-Second Chair Stand* 55 -1.11 ± 4.06 Not established
Grip Strength (kg) 108 -3.89 ± 8.89 Not established
6-Minute Walk Distance (m)* 107 -105.15 ± 100.93 >50 m

*No reference values were found for the 50–59 age group. One subject did not perform this test.

Relationship of Nadir CD4 Count with Physical Function
  Total (n=108) <200 cells/mm³ (n=73) ≥350 cells/mm³ (n=35) p-value Normal or Desired Value
Gait Speed – Usual Speed (m/s) 1.17 ± 0.83 1.15 ± 0.79 1.20 ± 0.92 0.36 >1.2
Gait Speed – Maximal Speed (m/s) 1.76 ± 0.37 1.76 ± 0.39 1.77 ± 0.34 0.74 N/A
30-Second Chair Stand 12.67 ± 4.12 12.66 ± 4.31 12.69 ± 3.76 0.86 >16
Grip Strength (kg) 33.36 ± 9.62 33.19 ± 9.43 33.70 ± 10.14 0.83 N/A
6-Minute Walk Distance (m) 428.38 ± 109.55 421.55 ± 111.34 442.64 ± 105.87 0.55 >597

*Note: ≥1.2 m/s is considered the walking speed needed to safely cross the street.

Acknowledgment

The authors would like to thank the subject for their participation. This work was supported by an investigator-initiated grant from the Duke University Center for AIDS research (CFAR Grant number AI064518), The Duke Pepper OAIC (OAIC grant number P30 AG028716), and the Duke Department of Medicine.

 

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