const
  wdFormatDocument                    =  0;
  wdFormatDocumentDefault             = 16;
  wdFormatDOSText                     =  4;
  wdFormatDOSTextLineBreaks           =  5;
  wdFormatEncodedText                 =  7;
  wdFormatFilteredHTML                = 10;
  wdFormatFlatXML                     = 19;
  wdFormatFlatXMLMacroEnabled         = 20;
  wdFormatFlatXMLTemplate             = 21;
  wdFormatFlatXMLTemplateMacroEnabled = 22;
  wdFormatHTML                        =  8;
  wdFormatPDF                         = 17;
  wdFormatRTF                         =  6;
  wdFormatTemplate                    =  1;
  wdFormatText                        =  2;
  wdFormatTextLineBreaks              =  3;
  wdFormatUnicodeText                 =  7;
  wdFormatWebArchive                  =  9;
  wdFormatXML                         = 11;
  wdFormatXMLDocument                 = 12;
  wdFormatXMLDocumentMacroEnabled     = 13;
  wdFormatXMLTemplate                 = 14;
  wdFormatXMLTemplateMacroEnabled     = 15;
  wdFormatXPS                         = 18;
  wdFormatOfficeDocumentTemplate      = 23;
  wdFormatMediaWiki                   = 24;

const
  wdDoNotSaveChanges = $00000000;

// Convert a DOC or DOCX document to PDF, DOC or DOCX
function ConvertWordToPDF(const InFilename, OutFilename: string: OutFormat: Integer = wdFormatPDF): Boolean;
var
  wordApp: OleVariant;
begin
  Result := False;
  try
    wordApp := CreateOleObject('Word.Application');
    if VarIsEmpty( wordApp ) then
      exit;

    wordApp.Visible := False;
    wordApp.Documents.Open( InFilename,
                            false,   // ConfirmConversions
                            true );  // ReadOnly

    wordApp.ActiveDocument.SaveAs2( OutFilename, OutFormat );  

    wordApp.Quit(wdDoNotSaveChanges, EmptyParam, EmptyParam);
    wordApp := Unassigned;

    Result := True;
  except
    // Word error
  end;
end;