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Single group proportional meta -analysis*

  • 1.  Single group proportional meta -analysis*

    Posted Tue May 07, 2024 07:57 AM

    Hello,


    I am trying to do single group proportional meta analysis (on SPSS 29 version) but I see there is only option for two group analysis. This is for meta-analysis in systematic review; my data is sample size and prevalence. Based on this raw data, I want to get a forest plot and funnel lot. Can someone guide me please?

    thank you



    Pallavi MPH

    wiss.Mitarbeiterin

     

    Hochschule Emden/Leer

    Raum G267

    Constantiaplatz 4

    26723 Emden


    Tel: +491764367867

    » www.hs-emden-leer.de



     





  • 2.  RE: Single group proportional meta -analysis*

    Posted Mon June 03, 2024 10:18 AM

    I suspect you will have to use the pre-calculated effect size approach.  Here is an example using the 7 studies shown on this Stata page:

    https://www.stata.com/new-in-stata/meta-analysis-prevalence-proportions/

    I chose to use the logit transformation.  I could not find logit() and invlogit() functions, so I had to roll my own.  Here's the code.

    NEW FILE.
    DATASET CLOSE ALL.
    DATA LIST LIST / Study N events (3F8.0).
    BEGIN DATA 
    1 14200 1178
    2 51000 4641
    3 86400 3974
    4 68000 2856
    5 43400 1519
    6 15500  604
    7 54500 5341
    END DATA.
    DATASET NAME raw.

    COMPUTE nonevents = N - events.
    COMPUTE p = events/N.
    COMPUTE q = 1-p.
    COMPUTE y = ln(p/q).
    COMPUTE sey = SQRT(1/events + 1/nonevents).
    VARIABLE LABELS 
        y "Y = logit(p)"
        sey "SE(Y)"
    .
    LIST y sey.

    * OMS.
    DATASET DECLARE  PooledEst.
    OMS
      /SELECT TABLES
      /IF COMMANDS=['Meta ES Continuous'] SUBTYPES=['Effect Size Estimates']
      /DESTINATION FORMAT=SAV NUMBERED=TableNumber_
       OUTFILE='PooledEst' VIEWER=YES.
    * OMS.
    DATASET DECLARE  IndStud.
    OMS
      /SELECT TABLES
      /IF COMMANDS=['Meta ES Continuous'] SUBTYPES=['Effect Size Estimates for Individual Studies']
      /DESTINATION FORMAT=SAV NUMBERED=TableNumber_
       OUTFILE='IndStud' VIEWER=YES.

    META ES CONTINUOUS
      /DATA ES=y  SE=sey  ID=Study  
      /CRITERIA CILEVEL=95 SCOPE=AVAILABLE
       CLASSMISSING=EXCLUDE MAXITER=100 MAXSTEP=5 
        CONVERGENCE=0.000001
      /INFERENCE MODEL=RANDOM ESTIMATE=REML ADJUSTSE=NONE
      /PRINT  INDIVIDUAL
      /FORESTPLOT  ADDCOLS=N events POSITION=RIGHT
       ANNOTATIONS=HOMOGENEITY HETEROGENEITY TEST.

    OMSEND.

    DATASET ACTIVATE IndStud WINDOW = FRONT.
    * Apply inverse-logit transformation: exp(x)/(1+exp(x)).
    COMPUTE p = EXP(EffectSize)/(1+EXP(EffectSize)).
    COMPUTE lb = EXP(Lower)/(1+EXP(Lower)).
    COMPUTE ub = EXP(Upper)/(1+EXP(Upper)).
    FORMATS p lb ub (F8.3).
    LIST p lb ub.

    DATASET ACTIVATE PooledEst.
    * Apply inverse-logit transformation: exp(x)/(1+exp(x)).
    COMPUTE p = EXP(EffectSize)/(1+EXP(EffectSize)).
    COMPUTE lb = EXP(Lower)/(1+EXP(Lower)).
    COMPUTE ub = EXP(Upper)/(1+EXP(Upper)).
    FORMATS p lb ub (F8.3).
    LIST p lb ub.
    * This pooled estimate matches the result 
    * I get using Stata. 

    Here are the results from that last LIST:

           p       lb       ub 
     
        .057     .041     .079 

    For comparison, here are the results from Stata.  You'll have to display in a fixed font to make it more readable.

    . meta summarize, transform(invlogit) 

      Effect-size label: Logit proportion
            Effect size: _meta_es
              Std. err.: _meta_se

    Meta-analysis summary                     Number of studies =      7
    Random-effects model                      Heterogeneity:
    Method: REML                                          tau2 =  0.2220
                                                        I2 (%) =   99.82
                                                            H2 =  560.84

    --------------------------------------------------------------------
                Study |     Proportion    [95% conf. interval]  % weight
    ------------------+-------------------------------------------------
              Study 1 |          0.083       0.079       0.088     14.27
              Study 2 |          0.091       0.089       0.094     14.31
              Study 3 |          0.046       0.045       0.047     14.31
              Study 4 |          0.042       0.041       0.044     14.30
              Study 5 |          0.035       0.033       0.037     14.28
              Study 6 |          0.039       0.036       0.042     14.22
              Study 7 |          0.098       0.096       0.101     14.31
    ------------------+-------------------------------------------------
      invlogit(theta) |          0.057       0.041       0.079
    --------------------------------------------------------------------
    Test of theta = 0: z = -15.70                    Prob > |z| = 0.0000
    Test of homogeneity: Q = chi2(6) = 3474.75         Prob > Q = 0.0000

    I hope this helps. 



    ------------------------------
    Bruce Weaver
    ------------------------------