For 1975 and 1978, gallstones or gallbladder trouble records were defined as those condition records with any of the following codes in the variable DCICDCOD in the original NHIS public use files:

• "5740" ("Cholelithiasis with acute cholecystitis")

• "5741" ("Cholelithiasis with cholecystitis, other")

• "5749" ("Other and unspecified cholelithiasis")

The above condition code values come from the International Classification of Diseases (ICD) codes Revision 8.

Gallstones or gallbladder trouble records were also defined as those condition records with a code of "179" ("Gallbladder trouble, not otherwise specified") in the variable DIAGR1 in the original NHIS public use files. This condition code value comes from NCHS's Diagnostic Recode #1: Diseases, Injuries, and Impairments and from, respectively.

Additionally, to be considered "chronic," gallstone and gallbladder trouble records must have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

For 1979-1981, gallstones or gallbladder trouble records were defined as those condition records with any of the following codes in the variable DCICDCOD in the original NHIS public use files:

• "5740" ("Calculus of gallbladder with acute choecystitis")

• "5741" ("Calculus of gallbladder with other cholecystitis")

• "5742" ("Calculus of gallbladder without mention of cholecystitis")

• "5743" ("Calculus of bile duct with acute cholecystitis")

• "5744" ("Calculus of bile duct with other cholecystitis")

• "5745" ("Calculus of bile duct without mention of cholecystitis")

• "5750" ("Acute cholecystitis")

• "5751" ("Other cholecystitis")

• "5752" ("Obstruction of gallbladder")

• "5753" ("Hydrops of gallbladder")

• "5754" ("Perforation of gallbladder")

• "5755" ("Fistula of gallbladder")

• "5756" ("Cholesterolosis of gallbladder")

• "5758" ("Other specified disorders of gallbladder")

• "5759" ("Unspecified disorder of gallbladder")

These condition code values come from the International Classification of Diseases (ICD) codes Revision 9. As with earlier years, to be considered "chronic," gallstone and gallbladder trouble records must also have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

For 1982 to 1996, gallstones or gallbladder trouble records were defined in one of two ways.

First, those condition records with any of the following codes in the variable DCICDCOD in the original NHIS public use files were considered gallbladder trouble records:

• "5750" ("Acute cholecystitis")

• "5751" ("Other cholecystitis")

• "5752" ("Obstruction of gallbladder")

• "5753" ("Hydrops of gallbladder")

• "5754" ("Perforation of gallbladder")

• "5755" ("Fistula of gallbladder")

• "5756" ("Cholesterolosis of gallbladder")

• "5758" ("Other specified disorders of gallbladder")

• "5759" ("Unspecified disorder of gallbladder")

These condition code values come from the International Classification of Diseases (ICD) codes Revision 9. As with earlier years, to be considered "chronic," gallstone and gallbladder trouble records must also have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

Second, those condition records with a code of "301" ("Gallbladder stones") in the variable C1CONDRC in the original NHIS public use files were considered gallstone records. This condition code value comes from NCHS's Diagnostic Recode C: Chronic Conditions and Impairments.