Demonstration analyses for Doug Dluzen's expression data

Descriptive statistics:

There are 80 participants in these data.

     HNDid                 DOB                  Age0       Age0grp    Age0med      Sex        Race     PovStat  
 Min.   :8031107802   Min.   :1945-12-28   Min.   :50.0   30-34: 0   Below: 0   Women:80   White:40   Above:57  
 1st Qu.:8139538326   1st Qu.:1949-01-04   1st Qu.:53.0   35-39: 0   Above:80   Men  : 0   AfrAm:40   Below:23  
 Median :8154425602   Median :1951-03-30   Median :55.0   40-44: 0                                              
 Mean   :8163593397   Mean   :1951-06-25   Mean   :54.8   45-49: 0                                              
 3rd Qu.:8191917627   3rd Qu.:1953-11-17   3rd Qu.:57.0   50-54:37                                              
 Max.   :8223284501   Max.   :1957-07-05   Max.   :59.0   55-59:43                                              
                                                          60-64: 0                                              
 Hyperten   Smoker      drawDate            DRUnumber      miR.30c.5p       miR.20a.5p      miR.4763.5p    
 No :39   Never:80   Min.   :2004-10-16   Min.   :  93   Min.   : 0.148   Min.   : 0.088   Min.   : 0.012  
 Yes:41   Ever : 0   1st Qu.:2005-11-03   1st Qu.: 722   1st Qu.: 0.545   1st Qu.: 0.468   1st Qu.: 0.611  
                     Median :2006-12-09   Median :1226   Median : 0.729   Median : 0.815   Median : 1.365  
                     Mean   :2006-11-04   Mean   :1238   Mean   : 1.667   Mean   : 1.752   Mean   : 2.014  
                     3rd Qu.:2007-09-21   3rd Qu.:1708   3rd Qu.: 1.632   3rd Qu.: 2.056   3rd Qu.: 2.308  
                     Max.   :2008-12-18   Max.   :2460   Max.   :15.499   Max.   :10.611   Max.   :18.274  

 miR.103a.2.5p   CMVplus      PhysBMI          Chol          HDL          LDLcalc         Triglyc            CRP       
 Min.   :0.000   No  : 8   Min.   :20.1   Min.   :114   Min.   :30.0   Min.   : 15.8   Min.   :  39.0   Min.   : 0.15  
 1st Qu.:0.202   Yes :31   1st Qu.:26.8   1st Qu.:176   1st Qu.:45.8   1st Qu.: 99.6   1st Qu.:  74.8   1st Qu.: 1.22  
 Median :0.388   NA's:41   Median :30.5   Median :197   Median :54.5   Median :116.6   Median :  98.0   Median : 3.45  
 Mean   :0.433             Mean   :31.7   Mean   :198   Mean   :56.3   Mean   :116.3   Mean   : 125.5   Mean   : 6.66  
 3rd Qu.:0.655             3rd Qu.:35.8   3rd Qu.:214   3rd Qu.:65.0   3rd Qu.:131.8   3rd Qu.: 127.0   3rd Qu.: 7.67  
 Max.   :0.992             Max.   :54.6   Max.   :363   Max.   :92.0   Max.   :226.0   Max.   :1110.0   Max.   :48.70  
                                                                                                        NA's   :2      
 heartDis  Menopause  rxHRT        BPdia          BPsys      PhysRespRate  PhysPulseRadial rxHypercholesterolemia
 No  :74   No  : 6   No  :76   Min.   :50.0   Min.   : 93   Min.   :12.0   Min.   : 56.0   Min.   :0.000         
 Yes : 3   Yes :69   Yes : 2   1st Qu.:66.8   1st Qu.:111   1st Qu.:12.0   1st Qu.: 66.0   1st Qu.:0.000         
 NA's: 3   NA's: 5   NA's: 2   Median :73.0   Median :120   Median :16.0   Median : 72.0   Median :0.000         
                               Mean   :72.3   Mean   :123   Mean   :15.4   Mean   : 73.4   Mean   :0.179         
                               3rd Qu.:78.0   3rd Qu.:130   3rd Qu.:16.0   3rd Qu.: 78.0   3rd Qu.:0.000         
                               Max.   :96.0   Max.   :171   Max.   :20.0   Max.   :100.0   Max.   :1.000         
                               NA's   :4      NA's   :3     NA's   :4      NA's   :5       NA's   :2             

Regression analyses

Perform regression of expression levels on race, poverty status, age, and selected interactions.

(1) All interactions

                            miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                              0.050          0.114           0.091             0.108    
RaceAfrAm                       -2.064         -6.528          -5.252            -1.611    
PovStatBelow                     5.502         -3.129          31.453            -5.575 *  
Age0                            -0.018          0.015           0.073            -0.026    
RaceAfrAm:PovStatBelow         -14.805         -8.233          -9.526             3.538    
RaceAfrAm:Age0                   0.050          0.142           0.111             0.029    
PovStatBelow:Age0               -0.095          0.066          -0.569             0.102 *  
RaceAfrAm:PovStatBelow:Age0      0.241          0.118           0.153            -0.064    

(2) Eliminate 3-way because none of them were significant

                       miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                         0.046          0.112           0.089             0.091    
RaceAfrAm                  -5.614         -8.275          -7.511            -0.662    
PovStatBelow               -1.281         -6.467          27.137 *          -3.761 *  
Age0                       -0.050          0.000           0.053            -0.018    
RaceAfrAm:PovStatBelow     -1.563         -1.717          -1.100            -0.003    
RaceAfrAm:Age0              0.115          0.174           0.153             0.012    
PovStatBelow:Age0           0.028          0.127          -0.491 *           0.069 *  

(3) Analyze just main effects and significant interactions

                  miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                    0.018          0.070           0.074             0.087    
RaceAfrAm              0.263          0.786           0.541             0.002    
PovStatBelow          -3.175         -8.652          25.647 *          -3.791 *  
Age0                   0.006          0.084           0.127            -0.012    
PovStatBelow:Age0      0.046          0.149          -0.475 *           0.069 *  

(4) Add covariates to (3)

                  miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                    0.022          0.083           0.102             0.106    
RaceAfrAm              0.276          0.872           0.385             0.024    
PovStatBelow          -3.247        -10.527          26.907 *          -4.249 ** 
Age0                   0.016          0.097           0.150            -0.012    
HypertenYes           -0.212         -0.329          -0.503            -0.007    
PhysBMI                0.020          0.033          -0.032             0.004    
Chol                  -0.000          0.003          -0.006             0.001    
PovStatBelow:Age0      0.047          0.183          -0.497 *           0.078 ** 

There are differences in miR.4763.5p and miR.103a.2.5p associated with poverty status and its interaction with age, but no significant effects for miR.30c.5p and miR.20a.5p.

These plots illustrate the direction of the effects.

plot of chunk Plt1.3

plot of chunk Plt1.4

An outlier is apparent in the analyses for miR.4763.5p that may be responsible for the significant effects. Excluding the potential outlier makes little difference in the results when the 4 regressions were re-run.

                            miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                              0.048          0.111           0.130             0.116    
RaceAfrAm                       -1.592         -6.937          12.582            -2.140    
PovStatBelow                     5.502         -3.129          31.453 *          -5.575 ** 
Age0                            -0.018          0.015           0.073            -0.026    
RaceAfrAm:PovStatBelow         -15.277         -7.824         -27.360             4.067    
RaceAfrAm:Age0                   0.041          0.150          -0.226             0.040    
PovStatBelow:Age0               -0.095          0.066          -0.569 *           0.102 ** 
RaceAfrAm:PovStatBelow:Age0      0.249          0.111           0.491            -0.074    
                       miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                         0.043          0.110           0.100             0.092    
RaceAfrAm                  -5.403         -8.627           5.084            -1.004    
PovStatBelow               -1.437         -6.206          17.801 *          -3.508 *  
Age0                       -0.050          0.001           0.010            -0.017    
RaceAfrAm:PovStatBelow     -1.550         -1.738          -0.354            -0.023    
RaceAfrAm:Age0              0.111          0.181          -0.089             0.019    
PovStatBelow:Age0           0.030          0.122          -0.322 *           0.064 *  
                  miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                    0.017          0.067           0.093             0.084    
RaceAfrAm              0.242          0.780           0.107             0.013    
PovStatBelow          -3.554         -8.766          17.697 *          -3.596 *  
Age0                  -0.001          0.082          -0.031            -0.008    
PovStatBelow:Age0      0.054          0.152          -0.323 *           0.065 *  
                  miR.30c.5p     miR.20a.5p     miR.4763.5p     miR.103a.2.5p    
Rsq                    0.021          0.080           0.104             0.101    
RaceAfrAm              0.259          0.867           0.026             0.033    
PovStatBelow          -3.605        -10.635          19.161 *          -4.066 *  
Age0                   0.008          0.094          -0.030            -0.008    
HypertenYes           -0.186         -0.321           0.056            -0.021    
PhysBMI                0.021          0.033          -0.024             0.004    
Chol                   0.000          0.003          -0.003             0.001    
PovStatBelow:Age0      0.054          0.185          -0.350 *           0.074 *