Gaby Heuchan
Gaby Heuchan

Reputation: 1

gls with repeated measures of BMI over time with complex samples (twins) in R

I'm running a generalised least squares (gls) to model BMI trajectories with age by intake of a nutrient. My sample is a cohort of twins, so data are clustered within individuals (twinID; due to repeated height and weight measures over time) and within families (famID; due to closer similarities in BMI between twins than other individuals).

My code currently is:

#model 1
gls_21m_obs <- long_data_m %>% 
  gls(BMI ~  ns(age,3) * ns(Nutrient,2),
      data=., 
      correlation = corCAR1(form = ~age|twinID),
      na.action = na.omit)

and

#model 2
INT_gls_21m_adj_filt <- long_data_m %>% filter(age>= ageT2_m) %>%    #filtering out cases for pre-diary BMI
  gls(BMI ~  ns(age,3) * ns(Nutrient,2) + ns(age,3) * Sex + ns(age,3) * CSDS_weight_0m + ns(age,3) * CweeksDelivery
      + ns(age,3) * Cincome + ns(age,3) * MatQual + ns(age,3) * ethnicity + ns(age,3) * Ccigarettes + 
        ns(age,3) * diabetes + ns(age,3) * CBMI_mother + ns(age,3) * NSSEC3 + ns(age,3) * CIMD + 
        ns(age,3) * FeedingModality_3 + ns(age,3) * closest_BMI_T2 ,
      data=., 
      correlation = corCAR1(form = ~age|twinID),
      na.action = na.omit)

summary(INT_gls_21m_adj_filt)

I don't know how to add in adjustment for clustering within families. I don't think gls works with the survey package, and adding weights = varIdent(form = ~ 1 | twinID/famID), as suggested by ChatGPT makes the whole thing stop working.

weights = varIdent(form = ~ 1 | twinID/famID), <- this made the model stop working (R just took ages to try and run it so I stopped it)

I also tried the following:

#model
gls_21m_obs_Xformula <- long_data_m %>% filter(FormulaFeeders== 0) %>% 
  gls(BMI ~  ns(age,3) * ns(Nutrient,2),
      data=., 
      correlation = corCAR1(form = ~age|twinID/famID),
      na.action = na.omit)

But the output was identical with the addition of /famID to without it

Sample data (apologies, it is in long format):

   twinID famID  Nutrient  ageT2_m Sex CSDS_weight_0m CweeksDelivery CSES_composite    Cincome MatQual ethnicity Zygosity_new Ccigarettes diabetes CBMI_mother NSSEC3
1   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
2   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
3   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
4   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
5   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
6   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
7   10031  1003       NA       NA   1      1.6123552      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
8   10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
9   10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
10  10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
11  10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
12  10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
13  10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
14  10032  1003       NA       NA   1      1.7296108      0.7976589     -2.2331242 -4.5410545       1         1            1  -0.7312003        2   0.8570732      0
15  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
16  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
17  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
18  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
19  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
20  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
21  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
22  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
23  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
24  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
25  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
26  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
27  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
28  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
29  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
30  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
31  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
32  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
33  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
34  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
35  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
36  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
37  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
38  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
39  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
40  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
41  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
42  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
43  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
44  10041  1004 17.80472 20.10678   2     -0.1549409     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
45  10042  1004 17.35859 20.10678   2     -2.4764245     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
46  10042  1004 17.35859 20.10678   2     -2.4764245     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
47  10042  1004 17.35859 20.10678   2     -2.4764245     -4.2023411      0.7068758  0.4589455       4         1            1  -0.7312003        2   0.9187060      2
         CIMD FeedingModality_3       age      BMI closest_BMI_T2
1   5.1551724                 2 12.254648       NA             NA
2   5.1551724                 2 22.373768 17.28843             NA
3   5.1551724                 2 25.560634 17.02422             NA
4   5.1551724                 2  0.000000       NA             NA
5   5.1551724                 2  2.595489       NA             NA
6   5.1551724                 2  6.767983       NA             NA
7   5.1551724                 2  9.692014       NA             NA
8   5.1551724                 2  0.000000       NA             NA
9   5.1551724                 2  2.595489       NA             NA
10  5.1551724                 2  6.767983       NA             NA
11  5.1551724                 2  9.692014       NA             NA
12  5.1551724                 2 12.254648       NA             NA
13  5.1551724                 2 22.373768 17.43197             NA
14  5.1551724                 2 25.560634 16.79286             NA
15 -0.8448276                 2 51.876916 14.96599       15.62500
16 -0.8448276                 2 35.712608 15.55664       15.62500
17 -0.8448276                 2 24.575005 15.67717       15.62500
18 -0.8448276                 2 90.809244 15.25128       15.62500
19 -0.8448276                 2 14.620157 15.55531       15.62500
20 -0.8448276                 2 39.490851 15.51247       15.62500
21 -0.8448276                 2 76.780464 15.01189       15.62500
22 -0.8448276                 2 55.852285 14.67377       15.62500
23 -0.8448276                 2 85.848247 15.28899       15.62500
24 -0.8448276                 2  0.000000       NA       15.62500
25 -0.8448276                 2 94.718904 15.47313       15.62500
26 -0.8448276                 2 72.377990 14.77378       15.62500
27 -0.8448276                 2 83.844135 15.05576       15.62500
28 -0.8448276                 2  3.055449       NA       15.62500
29 -0.8448276                 2 12.254648       NA       15.62500
30 -0.8448276                 2 61.536076 14.62810       15.62500
31 -0.8448276                 2  9.034928 16.47924       15.62500
32 -0.8448276                 2  5.815208       NA       15.62500
33 -0.8448276                 2 20.303948 15.62500       15.62500
34 -0.8448276                 2 60.911844 14.62810       15.62500
35 -0.8448276                 2 80.098747 15.08621       15.62500
36 -0.8448276                 2 68.271204 14.98724       15.62500
37 -0.8448276                 2 30.061671 15.09479       15.62500
38 -0.8448276                 2 33.741351 15.03064       15.62500
39 -0.8448276                 2 74.020704 15.15851       15.62500
40 -0.8448276                 2 41.166419 15.72962       15.62500
41 -0.8448276                 2 48.032965 14.70450       15.62500
42 -0.8448276                 2 45.010371 16.06020       15.62500
43 -0.8448276                 2 16.919957       NA       15.62500
44 -0.8448276                 2 28.024705 15.36674       15.62500
45 -0.8448276                 2 35.712608 14.37024       15.02314
46 -0.8448276                 2  0.000000       NA       15.02314
47 -0.8448276                 2 72.377990 13.87117       15.02314

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